Horticulture is the art and science of the cultivation of plants
Spatial allocation is primarily concerned with designating what kinds of activities can or will be done where on the landscape. Land-use zoning is a typical example of a spatial allocation problem in which the landscape is divided up into a set of multiple alternative uses such as industrial, commercial, residential, etc. Allocation to a particular use usually depends on intrinsic properties of the individual parcels as well as adjacency constraints.
Resource allocation has two meanings. One meaning refers to allocating a resource such as forest land to two or more designated uses. For example, forest land units could be allocated to timber production, recreation, etc. The second meaning is in the sense of allocating management resources. This second meaning is concerned with allocating time, materials, personnel, budget to landscape elements to accomplish management objectives such as protection, restoration, timber production, etc.
In wastewater treatment, a combination of step processes, usually physical in nature, that are designed to remove floating and settleable solids. Examples of process steps are screening and sedimentation.
In wastewater treatment, a combination of step processes, usually biochemical in nature, that are designed to remove primarily organic material. Examples of process steps are aeration and trickling filters.
Post-secondary treatment of wastewater designed to improve the quality of the water to the point where it can be put to a particular beneficial use. Generally, tertiary treatment steps remove nutrients (e.g., nitrogen and phosphorus) which are poorly removed by secondary treatment. Commonly used steps include coagulation and clarification.
The subsurface emplacement of ‘fluids’ through a bored, drilled, or driven ‘well’, or through a dug well, where the depth of the dug well is greater than the largest surface dimension.
An urban area is an area with an increased density of human-created structures in comparison to the areas surrounding it. This term is at one end of the spectrum of suburban and rural areas. An urban area is more frequently called a city or town.
Geodesy is the scientific discipline that deals with the measurement and representation of a planet, including its gravity field, in a three-dimensional time varying space. Besides the gravity field, geodesists study also geodynamical phenomena such as crustal motion, tides, and polar motion. For this they design global and national Control networks, using Space and terrestrial techniques while relying on datums and coordinate systems
Geophysics, a branch of Earth sciences, is the study of the Earth by quantitative physical methods, especially by seismic, electromagnetic, and radioactivity methods. The theories and techniques of geophysics are employed extensively in the planetary sciences in general.
Mechanics is the branch of physics concerned with the behaviour of physical bodies when subjected to forces or displacements, and the subsequent effect of the bodies on their environment.
Neotectonics is a subdiscipline of tectonics. It is the study of the motions and deformations of the Earth's crust (geological and geomorphological processes) which are current or recent in geologic time.[1] The term may also refer to the motions/deformations in question themselves. The corresponding time frame is referred to as the neotectonic period.
Planetary science, also known as planetology and closely related to planetary astronomy, is the science of planets, or planetary systems, and the solar system. [Wikipedia]
In plate tectonic theory earth history, at its simplest, is one of plates rifting into pieces diverging apart and new ocean basins being born, followed by motion reversal, convergence back together, subduction of the oceanic crust, plate collision, and mountain building. This cycle of opening and closing ocean basins is the Wilson Cycle . [Wikipedia]
Seismology (from the Greek seismos = earthquake and λόγος,logos = knowledge ) is the scientific study of earthquakes and the propagation of elastic waves through the Earth. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic, atmospheric, and artificial processes (such as explosions).
Tectonics is a field of study within geology concerned generally with the structures within the crust of the Earth (or other planets) and particularly with the forces and movements that have operated in a region to create these structures. Tectonics is concerned with the orogenies and tectonic development of cratons and tectonic terranes as well as the earthquake and volcanic belts which directly affect much of the global population. Tectonic studies are also important for understanding erosion patterns in geomorphology and as guides for the economic geologist searching for petroleum and metallic ores. A subfield of tectonics that deals with tectonic phenomena in the geologically recent period is called neotectonics.
Chemical substance, in chemistry, are material objects that can undergo various transformations related to artificial or natural phenomena [Wikipedia]
In chemistry, a mixture is when two or more different substances are mixed together but not combined chemically. The molecules of two or more different substances are mixed in the form of solutions, suspensions, and colloids. [Wikipedia]
In chemistry, a solution is a homogeneous mixture composed of two or more substances. In such a mixture, a solute is dissolved in another substance, known as a solvent. All solutions are characterized by interactions between the solvent phase and solute molecules or ions that result in a net decrease in free energy. [Wikipedia]
Fine particles of pulverized rock.
Aerosol having its origin over the continents with industrial, urban, agricultural, forest, and desert sources, with potential for high concentrations of hygroscopic aerosol.
The term for solid or liquid particles found in a gas. Some particles are large or dark enough to be seen as soot or smoke.
The Acorn worms or Enteropneusta are a hemichordate class of invertebrates. Acorn worms are classified in the phylum Hemichordata, closely related to the chordates. There are about 70 species of acorn worm in the world, the main species for research being Saccoglossus kowaleski. All species are infaunal benthos that either may be deposit feeders or suspension feeders. Some of these worms may grow to be very long; one particular species may reach a length of 2.5 meters (almost eight feet), although most acorn worms are much, much smaller.
An indicator species is any biological species that defines a trait or characteristic of the environment. For example, a species may delineate an ecoregion or indicate an environmental condition such as a disease outbreak, pollution, species competition or climate change. Indicator species can be among the most sensitive species in a region, acting as an early warning to monitoring biologists.
A chemical compound is a pure chemical substance consisting of two or more different chemical elements[1][2][3] that can be separated into simpler substances by chemical reactions[4] and that have a unique and defined chemical structure. Chemical compounds consist of a fixed ratio of atoms[3] that are hold together in a defined spatial arrangement by chemical bonds. [Wikipedia]
A salt is defined as the product formed from the neutralization reaction of acids and bases. Salts are ionic compounds composed of cations (positively charged ions) and anions (negative ions) so that the product is electrically neutral (without a net charge). [Wikipedia]
An element such as copper that forms sulphide minerals if sufficient sulphur is available.
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. The term is also used to refer to a pure chemical substance composed of atoms with the same number of protons. [Wikipedia]
A metal is a chemical element whose atoms readily lose electrons to form positive ions (cations), and form metallic bonds between other metal atoms and ionic bonds between nonmetal atoms.[Wikipedia]
A nearly colorless gas, it is a very strong absorber of ultraviolet radiation, and the presence of the ozone layer in the upper atmosphere provides an ozone shield that prevents dangerous radiation from reaching the earth's surface.
An aircraft is a vehicle which is able to fly through the air (or through any other atmosphere). All the human activity which surrounds aircraft is called aviation. (Most rocket vehicles are not aircraft because they are not supported by the surrounding air).
A borehole is the generalised term for any narrow shaft drilled in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes including the extraction of water or fluid (such as oil) or gases (such as natural gas or methane), as part of a geotechnical investigation or environmental site assessment, for mineral exploration, or as a pilot hole for installing piers or underground utilities.
A bored, drilled or driven shaft, or a dug hole, whose depth is greater than the largest surface dimension.
An alloy is a partial or complete solid solution of one or more elements in a metallic matrix. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may be homogeneous in distribution depending on thermal (heat treatment) history. Alloys usually have different properties from those of the component elements. [Wikipedia]
LIDAR (Light Detection and Ranging) is an optical remote sensing technology that measures properties of scattered light to find range and/or other information of a distant target. The prevalent method to determine distance to an object or surface is to use laser pulses. Like the similar radar technology, which uses radio waves instead of light, the range to an object is determined by measuring the time delay between transmission of a pulse and detection of the reflected signal. LIDAR technology has application in archaeology, geography, geology, geomorphology, seismology, remote sensing and atmospheric physics.
A devise used to measure groundwater pressure head at a point in the subsurface.
A temperature-measuring system in which the thermally sensitive element is located at a distance from the indicating element.
A device used to measure the moisture tension in the unsaturated zone.
An anion is an ion that has more electrons than protons such that the atom or molecule is negatively charged. [Wikipedia]
An cation is an ion that has more protons than electrons such that the atom or molecule is positively charged. [Wikipedia]
An ion is an atom or molecule where the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. [Wikipedia]
In the scientific sense the term glass is often extended to all amorphous solids (and melts that easily form amorphous solids), including plastics, resins, or other silica-free amorphous solids. [Wikipedia]
Hematite, also spelled as hæmatite, is the mineral form of Iron(III) oxide (Fe2O3), one of several iron oxides. Hematite crystallizes in the rhombohedral system, and it has the same crystal structure as ilmenite and as corundum. Hematite is a mineral, colored black to steel or silver-gray, brown to reddish brown, or red. It is mined as the main ore of iron [Wikipedia]
Magnetite is a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides and a member of the spinel group. [Wikipedia]
A mineral is a naturally occurring solid formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties [Wikipedia]
A mineraloid is a mineral-like substance that does not demonstrate crystallinity. Mineraloids possess chemical compositions that vary beyond the generally accepted ranges for specific minerals. For example, obsidian is an amorphous glass and not a crystal. [Wikipedia]
The majority of minerals are non-metallic, i.e., they are not elemental minerals which are of metal elements or alloys of metals. [Wikipedia]
Coal is a readily combustible black or brownish-black sedimentary rock. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. It is composed primarily of carbon along with variable quantities of other elements, chiefly sulfur, hydrogen, oxygen and nitrogen. [Wikipedia]
Deposition is the geological process by which material is added to a landform or land mass. Fluids such as wind and water, as well as sediment gravity flows, transport previously eroded sediment, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of sediment. [Wikipedia]
Fossil fuels or mineral fuels are fuels formed by the natural resources such as anaerobic decomposition of buried dead organisms that lived up to 300 million years ago. These fuels contain high percentage of carbon and hydrocarbons. [Wikipedia]
Natural gas is a gas consisting primarily of methane. It is found associated with fossil fuels, in coal beds, as methane clathrates, and is created by methanogenic organisms in marshes, bogs, and landfills. It is an important fuel source, a major feedstock for fertilizers, and a potent greenhouse gas. [Wikipedia]
Natural resources (economically referred to as land or raw materials) are naturally forming substances that are considered valuable in their relatively unmodified (natural) form. [Wikipedia]
An oil is a substance that is in a viscous liquid statel (‘oily’) at ambient temperatures or slightly warmer, and is both hydrophobic (immiscible with water) and lipophilic (miscible with other oils, literally). This generag definition includes compound classes with otherwise unrelated chemical structures, properties, and uses, including vegetable oils, resochemical oils, and volatile essential oils. Oil is a nonpolar substance. [Wikipedia]
Petroleum or crude oil is a naturally occurring, flammable liquid found in rock formations in the Earth consisting of a complex mixture of hydrocarbons of various molecular weights, plus other organic compounds. [Wikipedia]
Chlorinated hydrocarbons consist of simple hydrocarbons in which one or more hydrogen atoms have been replaced with chlorine.
Chlorophyll is a green pigment found in most plants, algae, and cyanobacteria. Chlorophyll absorbs light most strongly in the blue and red but poorly in the green portions of the electromagnetic spectrum, hence the green color of chlorophyll-containing tissues like plant leaves.
An organochloride, organochlorine, or chlorocarbon, is an organic compound containing at least one covalently bonded chlorine atom. Their wide structural variety and divergent chemical properties lead to a broad range of uses.
Gamma rays are a form of electromagnetic radiation or light emission of frequencies produced by sub-atomic particle interactions, such as electron-positron annihilation or radioactive decay. Gamma rays are generally characterized as electromagnetic radiation having the highest frequency and energy, and also the shortest wavelength, within the electromagnetic spectrum, i.e. high energy photons. Due to their high energy content, they can cause serious damage when absorbed by living cells.
A collective name for the two baryons: neutron and the proton.
In botany, a fruit is the ripened ovary—together with seeds—of a flowering plant. In many species, the fruit incorporates the ripened ovary and surrounding tissues. Fruits are the means by which flowering plants disseminate seeds.
Mangroves (generally) are trees and shrubs that grow in saline coastal habitats in the tropics and subtropics. The word is used in at least three senses, (1) most broadly to refer to the habitat and entire plant assemblage or mangal, for which the terms mangrove swamp and mangrove forest are also used, (2) to refer to all trees and large shrubs in the mangal, and (3) narrowly to refer to the mangrove family of plants, the Rhizophoraceae, or even more specifically just to mangrove trees of the genus Rhizophora. Mangals are found in depositional coastal environments where fine sediments, often with high organic content, collect in areas protected from high energy wave action.
n vascular plants, the root is the organ of a plant body that typically lies below the surface of the soil (compare with stem). However, this is not always the case, since a root can also be aerial (that is, growing above the ground) or aerating (that is, growing up above the ground or especially above water). On the other hand, a stem normally occurring below ground is not exceptional either (see rhizome). So, it is better to define root as a part of a plant body that bears no leaves, and therefore also lacks nodes. There are also important internal structural differences between stems and roots. The two major functions of roots are 1.) absorption of water and inorganic nutrients and 2.) anchoring the plant body to the ground. Roots also function in cytokinin synthesis, which supplies some of shoot needs. They often function in storage of food. The roots of most vascular plant species enter into symbiosis with certain fungi to form mycorrhizas, and a large range of other organisms including bacteria also closely associate with roots.
Fossils are the preserved remains or traces of animals, plants, and other organisms from the remote past. Fossils vary in size from microscopic, such as single bacterial cells [2] only one micrometer in diameter, to gigantic (macroscopic), such as dinosaurs and trees many meters long and weighing many tons. [Wikipedia]
A heterogeneous or conglomerate is a rock consisting of individual stones that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts.[1] Both conglomerates and breccias are characterized by clasts larger than sand (>2 mm). [Wikipedia]
Macrofossils are preserved organic remains large enough to be visible without a microscope. [Wikipedia]
A mélange is a large scale breccia, a mappable body of rock characterized by a lack of continuous bedding and the inclusion of fragments of rock of all sizes, contained in a fine-grained deformed matrix. The mélange typically consists of a jumble of large blocks of varied lithologies of altered oceanic crustal material and blocks of continental slope sediments in a sheared mudstone matrix. Some larger blocks of rock may be as much as 1 km across. [Wikipedia]
One of the major groups of rock that makes up the crust of the Earth; consists of pre-existing rock mass in which new minerals or textures are formed at higher temperatures and greater pressures than those present on the Earth's surface [wicktionary]
Meteoric substances are rocks that have composition significantly different from earth rocks. Meteorites have traditionally been divided into three broad categories: stony meteorites are rocks, mainly composed of silicate minerals; iron meteorites are largely composed of metallic iron-nickel; and, stony-iron meteorites contain large amounts of both metallic and rocky material. [Wikipedia]
Fossils which are of microscopic size such as bacteria. [Wikipedia]
Molasse refers to the sandstones, shales and conglomerates formed as terrestrial or shallow marine deposits in front of rising mountain chains deposited in a foreland basin, especially on top of flysch, for example that left from the rising Alps, or erosion in the Himalaya. These deposits are typically the non-marine alluvial and fluvial sediments of lowlands, as compared to deep-water flysch sediments. Sedimentation stops once the orogeny stops, or once the mountains have eroded flat. [Wikipedia]
Regolith (Greek: ‘blanket rock’) is a layer of loose, heterogeneous material covering solid rock (bedrock). It includes dust, soil, broken rock, and other related materials [Wikipedia]
Rock is a naturally occurring solid aggregate of minerals and/or mineraloids. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic. [Wikipedia]
One of the major groups of rock that makes up the crust of the Earth; formed by the deposition of either the weathered remains of other rocks, the results of biological activity, or precipitation from solution [wicktionary]
One of three basic types of flow lava. Aa is basaltic lava characterized by a rough or rubbly surface composed of broken lava blocks called clinker. [Wikipedia]
Volcanic rock (or lava) characteristically medium dark in color and containing 54 to 62 percent silica and moderate amounts of iron and magnesium.
Anorogenic granites are formed above volcanic ‘hot spot’ activity and have peculiar mineralogy and geochemistry. These granites are formed by melting of the lower crust under conditions that are usually extremely dry. The rhyolites of the Yellowstone caldera are examples of volcanic equivalents of A-type granite. [Wikipedia]
Basalt is the most common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey. On Earth, most basalt magmas have formed by decompression melting of the mantle. [Wikipedia]
A volcanic cone built entirely of loose fragmented material (pyroclastics.)
A steep volcanic cone built by both lava flows and pyroclastic eruptions
Volcanic rock (or lava) that characteristically is light in color and contains 62% to 69% silica and moderate a mounts of sodium and potassium.
Magma that has erupted onto the surface of the earth and cooled suffciently to form solid rock. [Wikipedia]
Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. The term combines the words ‘feldspar’ and ‘silica.’ Felsic minerals are usually light in color and have specific gravities less than 3. Common felsic minerals include quartz, muscovite, orthoclase, and the sodium-rich plagioclase feldspars. The most common felsic rock is granite. On the opposite side of the rock spectrum are the iron and magnesium-rich mafic and ultramafic minerals and rocks. [Wikipedia]
Hypabyssal are igneous rocks formed at a depth in between the plutonic and volcanic rocks. They are characterized by their porphyritic nature (porphyry). They consist of phenocrysts embedded in a fine-grained groundmass. [Wikipedia]
By definition, all igneous rock is formed from magma [Wikipedia]
Beneath the surface magma tends to cool slowly which allows for the growth of large crystals within the rock. Rocks formed in this way are intrusive or plutonic rocks. [Wikipedia]
Kimberlite is a type of potassic volcanic rock best known for sometimes containing diamonds. The general consensus reached on kimberlites is that they are formed deep within the mantle, at between 150 and 450 kilometres depth, from anomalously enriched exotic mantle compositions, and are erupted rapidly and violently, often with considerable carbon dioxide and other volatile components. [Wikipedia]
Magma that extrudes onto the surface of earth is called lava. [Wikipedia]
Mafic is an adjective describing a silicate mineral or rock that is rich in magnesium and iron; the term was derived by contracting ‘magnesium’ and ‘ferric’. Most mafic minerals are dark in color and the specific gravity is greater than 3. Common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt and gabbro. In terms of chemistry, mafic rocks are on the other side of the rock spectrum from the felsic rocks. The term roughly corresponds to the older basic rock class.Mafic lava, before cooling, has a low viscosity, in comparison to felsic lava, due to the lower silica content in mafic magma. Water and other volatiles can more easily and gradually escape from mafic lava, so eruptions of volcanoes made of mafic lavas are less explosively violent than felsic lava eruptions. Most mafic lava volcanoes are oceanic volcanoes, like Hawaii. [Wikipedia]
Magma is molten rock that is found beneath the surface of the Earth.Magma is a complex high-temperature fluid substance in 3 phases; a system of silicate liquid, solid minerals, and perhaps a vapor phase. [Wikipedia]
Obsidian, a type of quenched lava, is a silicic black volcanic glass [Wikipedia]
Pahoehoe is basaltic lava that has a smooth, billowy, undulating, or ropy surface. These surface features are due to the movement of very fluid lava under a congealing surface crust. [Wikipedia]
Pillow lava is the lava structure typically formed when lava emerges from an underwater volcanic vent or subglacial volcano or a lava flow enters the ocean. However, pillow lava can also form when lava is erupted beneath thick glacial ice. The viscous lava gains a solid crust on contact with the water, and this crust cracks and oozes additional large blobs or ‘pillows’ as more lava emerges from the advancing flow. Since water covers the majority of Earth's surface and most volcanoes are situated near or under bodies of water, pillow lava is very common. [Wikipedia]
A pluton is an intrusive igneous rock body that crystallized from a magma slowly cooling below the surface of the Earth. Plutons include batholiths, dikes, sills, laccoliths, lopoliths, and other igneous bodies. In practice, ‘pluton’ usually refers to a distinctive mass of igneous rock, typically kilometers in dimension, without a tabular shape like those of dikes and sills. Batholiths commonly are aggregations of plutons. The most common rock types in plutons are granite, granodiorite, tonalite, and quartz diorite. [Wikipedia]
Light-colored, frothy volcanic rock, usually of dacite or rhyolite composition, formed by the expansion of gas in erupting lava. Commonly seen as lumps or fragments of pea-size and larger, but can also occur abundantly as ash-sized particles.
A descriptive term, usually for rock, which results from explosive magma ejection [Wikipedia]
Volcanic rock (or lava) that characteristically is light in color, contains 69% silica or more, and is rich in potassium and sodium.
A low, steep-sided cone of spatter built up on a fissure or vent. It is usually of basaltic material.
Tephra is a collective term (generally plural) used for all material -- regardless of size-- ejected during an explosive volcanic eruption.
An extrusive rock intermediate in composition between trachyte and andesite.
An extrusive rock intermediate in composition between trachyte and basalt.
A group of fine-grained, generally porphyritic, extrusive igneous rocks having alkali feldspar and minor mafic minerals as the main components, and possibly a small amount of sodic plagioclase.
Rock formed of pyroclastic material.
A type of volcanic cone formed by the interaction of basaltic magma and water. Smaller and steeper than a tuff ring.
A wide, low-rimmed, well-bedded accumulation of hyalo-clastic debris built around a volcanic vent located in a lake, coastal zone, marsh, or area of abundant ground water.
The mantle is composed mostly of Ultramafic rocks (or see Igneous Primer) such as peridotite and dunite and their metamorphic equivalents (e.g. ecologite). [Wikipedia]
A mound of loose material that was ejected ballistically.
A massive pillar of rock more resistant to erosion than the lavas and pyroclastic rocks of a volcanic cone.
Volcanic rock is an igneous rock produced by extrusion from a volcano. It has various subtypes based on chemical composition and whether the extrusion was violent (pyroclastic) or slow (laval). [Wikipedia]
A xenocryst is an individual foreign crystal included within an igneous body. Examples of xenocrysts are quartz crystals in a silica-deficient lava and diamonds within kimberlite diatremes. [Wikipedia]
A xenolith is a rock fragment which becomes enveloped in a larger rock during the latter's development and hardening. The term xenolith is almost exclusively used to describe inclusions in igneous rock during magma emplacement and eruption [Wikipedia]
Volcanic ash that has fallen through the air from an eruption cloud. A deposit so formed is usually well sorted and layered.
A turbulent mixture of gas and rock fragments, most of which are ash-sized particles, ejected violently from a crater or fissure. The mass of pyroclastics is normally of very high temperature and moves rapidly down the slopes or even along a level surface.
Angular chunk of solid rock ejected during an eruption.
Fragment of molten or semi-molten rock, 2 1/2 inches to many feet in diameter, which is blown out during an eruption. Because of their plastic condition, bombs are often modified in shape during their flight or upon impact.
A rapid and unusually sudden sliding or flowage of unsorted masses of rock and other material. As applied to the major avalanche involved in the eruption of Mount St. Helens, a rapid mass movement that included fragmented cold and hot volcanic rock, water, snow, glacier ice, trees, and some hot pyroclastic material. Most of the May 18, 1980 deposits in the upper valley of the North Fork Toutle River and in the vicinity of Spirit Lake are from the debris avalanche.
A mixture of water-saturated rock debris that flows downslope under the force of gravity (also called lahar or mudflow).
In volcanology, particles that came out of a volcanic vent, traveled through the air or under water, and fell back on the ground surface or on the ocean floor. [Wikipedia]
A deposit formed by the flowing or intrusion of lava or magma into water, ice, or water-saturated sediment and its consequent granulation or shattering into small angular fragments.
A torrential flow of water-saturated volcanic debris down the slope of a volcano in response to gravity. A type of mudflow.
A flowage of water-saturated earth material possessing a high degree of fluidity during movement. A less-saturated flowing mass is often called a debris flow. A mudflow originating on the flank of a volcano is properly called a lahar.
Peat is an accumulation of partially decayed vegetation matter. Peat forms in wetlands or peatlands.
In oceanography, terrigenous sediments are those derived from the erosion of rocks on land; that is, that are derived from terrestrial environments. Consisting of sand, mud, and silt carried to sea by rivers, their composition is usually related to their source rocks; deposition of these sediments is largely limited to the continental shelf.
A varve is an annual layer of sediment or sedimentary rock.
Volcanic deposits are molten rock (lava), solid rocks and ash which surround a volcano crater. [Wikipedia]
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers.
Depth hoares are large crystals occurring at the base of a snowpack that form due to the fact that a snow crystal can grow over time as moisture freezes onto the crystal from vapor that is rising in the snowpack.
Firn is partially-compacted névé, a type of snow that has been left over from past seasons and has been recrystallized into a substance denser than névé. It is ice that is at an intermediate stage between snow and glacial ice. Firn has the appearance of wet sugar, but has a hardness that makes it extremely resistant to shovelling. It generally has a density greater than 550 kg/m³ and is often found underneath the snow that accumulates at the head of a glacier.
A white or milky and opaque granular deposit of ice formed by the rapid freezing of supercooled water drops as they impinge upon an exposed object.
A stochastic process that describes (among other things) the rapid and chaotic motion of particles suspended in a fluid at rest as a consequence of fluctuations in the rate at which fluid molecules collide with the particles.
Planetary phenomena are the movements of planets and the sun, including for example orbits, alignments, eclipses day and night cycles, and the change of seasons.
In meteorology, the result of radiative cooling of the earth's surface and adjacent air. Radiational cooling occurs, as is typical on calm, clear nights
A widespread body of air, the properties of which can be identified as 1) having been established while that air was situated over a particular region of the earth's surface (airmass source region), and 2) undergoing specific modifications while in transit away from the source region.
A statically stable layer at the top of the atmospheric boundary layer.
A migratory wavelike disturbance of the tropical easterlies.
Mountain waves, lee waves, or trapped lee waves in the air stream flowing over the mountain barrier that occur in association with foehn conditions. The Moazagotl is one example of a foehn wave made visible by lee-wave clouds.
A horizontal wavelike deformation of a front in the lower levels, commonly associated with a maximum of cyclonic circulation in the adjacent flow. It may develop into a wave cyclone.
An air layer with its base at the ground surface and in which temperature increases with height. These often form at night over land under clear skies and are statically stable. See inversion, lapse rate.
The occurrence of air temperature below 0 C (32F) that kills annual vegetation without formation of frost crystals on surfaces. See freeze, dry freeze, hard freeze, light freeze.
1. Any wave disturbance that is caused by, and is therefore stationary with respect to, some barrier in the fluid flow. Whether the wave is a gravity wave, inertia wave, barotropic wave, etc., will depend on the structure of the fluid and the dimensions of the barrier. 2. A mountain wave occurring to the lee of a mountain or mountain barrier. These waves can become visible in the form of lenticular or trapped lee-wave clouds.
The occurrence of air temperature below 0 C (32F) that kills some, but not all, annual vegetation. This often occurs in the 0 to -1 C (32 30 F) range.
A thin and more or less patchy deposit of hoarfrost on surface objects and vegetation.
A disturbance where the atmospheric feature has a Rossby number of order 1 and exhibits a horizontal scale comparable to the Rossby radius of deformation. For such systems, both ageostrophic advection and rotational influences are important.
The statically stable layer of air at the top of the atmospheric boundary layer. Because the troposphere is statically stable on the average (i.e., potential temperature increases with height), and because turbulence in the boundary layer causes potential temperatures to become somewhat well mixed there, conservation of heat requires that there be a potential temperature increase (i.e., a temperature step or inversion) at the top of the boundary layer. It is this inversion that separates the boundary layer from the rest of the troposphere by limiting the domain of turbulence. It is also responsible for trapping pollutants near the ground during fair weather.
The three-part change of the atmospheric boundary layer that typically occurs during fair weather over land on sunny days. In the early morning, the mixed layer is shallow, slowly deepening, cool (in a potential temperature sense), and is capped by the remains of the stable boundary layer from the previous night. In mid- to late morning, the top of the mixed layer exhibits rapid rise as heating eliminates the nocturnal inversion, and the mixed layer grows through the residual layer. The third stage in late morning and afternoon is that of a deep (order of 1?2 km) convective boundary layer of relatively constant depth.
The development of an area in the boundary layer (e.g., often observed on surface or 850-mb charts) where moisture values become higher than in the surrounding region. Moisture pooling typically occurs in an area of low-level convergence during the warm (growing) season, and can have a significant effect on convection initiation and evolution.
An atmospheric gravity wave, formed when stable air flow passes over a mountain or mountain barrier.
The lowering of temperature during night time, due to a net loss of radiant energy.
Ascending air flow caused by mountains. Mechanisms that produce the lifting fall into two broad categories: 1) the upward deflection of horizontal larger-scale flow by the orography acting as an obstacle or barrier; or 2) the daytime heating of mountain surfaces to produce anabatic flow along the slopes and updrafts in the vicinity of the peaks.
Sunlight, in the broad sense, is the total spectrum of the electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the atmosphere, and the solar radiation is obvious as daylight when the Sun is above the horizon. This is usually during the hours known as day. Near the poles in summer, sunlight also occurs during the hours known as night and in the winter at the poles sunlight may not occur at any time. When the direct radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and heat. Radiant heat directly produced by the radiation of the sun is different from the increase in atmospheric temperature due to the radiative heating of the atmosphere by the sun's radiation.
An atmospheric optical phenomenon in which the observer appears to be engulfed in a uniformly white glow.
A principal cloud type (cloud genus) in the form of a gray or bluish (never white) sheet or layer of striated, fibrous, or uniform appearance.
The anvil-shaped cloud that comprises the upper portion of mature cumulonimbus clouds
a type of cloud
A cloud plume often observed to extend downwind from isolated, sharp, often pyramid-shaped mountain peaks, even on otherwise cloud-free days.
A synoptic-scale cloud pattern frequently observed in satellite imagery just prior to the onset of cyclogenesis.
A cloud variety composed of merged or separate elements that are elongated and parallel, either suggestive of ocean waves or arranged in ranks and files.
Colloquial expression for a cumulonimbus anvil that spreads upwind into relatively strong winds aloft.
A visible aggregate of minute water droplets and/or ice particles in the atmosphere above the earth's surface.
A principal cloud type (cloud genus), exceptionally dense and vertically developed, occurring either as isolated clouds or as a line or wall of clouds with separated upper portions.
A principal cloud type (cloud genus) in the form of individual, detached elements that are generally dense and posses sharp nonfibrous outlines.
An organized lifting zone of cumulus and towering cumulus clouds, connected to and extending outward from the mature updraft tower of a supercell or strong multicell convective storm.
Any cloudform associated with the foehn, usually referring to standing clouds of two types, orographic clouds and mountain wave clouds. Orographic clouds may include crest clouds and the foehn wall. Wave clouds may consist of lenticular (including altocumulus standing lenticular, or ACSL) clouds, lee-wave clouds and cloud bands, and rotors. See also Bishop wave, chinook arch, contessa di vento, Moazagotl.
The leeward edge of the orographic stratiform cap cloud as seen from the lee side of a mountain barrier, preceding or during a foehn or chinook event. The edge is generally abrupt and resembles a wall of cloud (?foehnwand? in German). This cloud often signifies the occurrence of orographic precipitation, especially snowfall in the cold season, over the peaks. See foehn cloud.
Small cumulus clouds that are everywhere negatively buoyant compared to the surrounding environment, but that exist because the inertia of the rising thermals feeding them from underneath is sufficient to penetrate the lifting condensation level (LCL). Morphologically, these are often cumulus humilis clouds and are typically found at the top of the convective boundary layer during daytime over land, when a strong temperature inversion aloft prevents the clouds from growing deeper. Compare active cloud, passive cloud.
A condensation cloud, typically funnel-shaped and extending outward from a cumuliform cloud, associated with a rotating column of air (a vortex) that may or may not be in contact with the ground. If the rotation is violent and in contact with the ground, the vortex is a tornado. Funnel clouds can occur through a variety of processes in association with convection. For example, small funnel clouds are infrequently seen extending from small, dissipating cumulus clouds in environments with significant vertical wind shear in the cloud-bearing layer.
1. Cloud forms that arise from Kelvin?Helmholtz waves. 2. Vortical structures that result from the growth and nonlinear development of unstable waves in a shear flow. The billows get their name from the instability responsible for the growth of the unstable waves, Kelvin?Helmholtz instability.
A long strip of cloud that sometimes lies against the southern base of Mount Etna in Sicily. It is said to herald rain.
Stratus cloud; a continuous cloud sheet capped by an inversion.
A commonly used term for clouds of the species lenticularis.
(Also called mammatus.) Hanging protuberances, like pouches, on the undersurface of a cloud. This supplementary cloud feature occurs mostly with cirrus, cirrocumulus, altocumulus, altostratus, stratocumulus, and cumulonimbus; in the case of cumulonimbus, mamma generally appear on the underside of the anvil (incus). See cloud classification.
A cloud forming in maritime air containing relatively low concentrations of cloud condensation nuclei. These clouds are characterized by a broader droplet size distribution and low droplet concentrations (some 100 cm-3). See continental cloud.
A cloud containing both water drops (supercooled at temperatures below 0?C) and ice crystals, hence a cloud with a composition between that of a water cloud and that of an ice- crystal cloud.
A cloud formed when two subsaturated volumes of moist air with different temperatures and vapor pressures mix isobarically and adiabatically to form a volume of moist air with an intermediate temperature and vapor pressure above the saturation value at that temperature.
A stationary bank of cirriform cloud marking the upper portion of the system of lenticular clouds formed in the lee wave produced by flow across the Sudeten Mountains in southeastern Germany; a type of foehn cloud.
A cloud that forms in the rising branches of mountain waves and occupies the crests of the waves. The most distinctive are the sharp-edged, lens-, or almond-shaped lenticular clouds, but a variety of stratocumulus, altocumulus, and cirrocumulus forms appear in both the main, vertically propagating waves and in the lee waves. See mountain wave, foehn cloud.
A principal cloud type (cloud genus), gray colored and often dark, rendered diffuse by more or less continuously falling rain, snow, sleet, etc., of the ordinary varieties and not accompanied by lightning, thunder, or hail.
(Rarely called luminous clouds.) Thin silvery-blue cirrus-like clouds frequently seen during summer twilight conditions at high latitudes (above 50?) in both hemispheres. They are the highest visible clouds in the atmosphere, occurring in the upper mesosphere at heights of about 85 km, and are closely related to the polar mesospheric clouds seen in satellite observations at similar altitudes over the summer polar cap. Noctilucent clouds are now known to consist of tiny ice particles with dimensions of the order of tens of nanometers, growing in the extreme cold of the summer polar mesopause region. The condensation nuclei on which the particles grow are thought to be either smoke and dust particles of meteoric origin or large hydrated positive ions. Strong upwelling of air from below, associated with a pole-to-pole meridional circulation in the upper mesosphere, is responsible for both the extreme cold and the upward flux of water vapor. Although water-vapor mixing ratios are very low (less than 10 parts per million by volume) in the region, the temperatures are also low enough to produce a high degree of supersaturation at times. Anomalously strong radar echoes from the region, known as polar summer mesospheric echoes, are also associated with the clouds. Compare nacreous clouds, polar stratospheric clouds.
Mountain clouds produced by orographic lifting of moist air to saturation.
A domelike protrusion above a cumulonimbus anvil, representing the intrusion of an updraft through its equilibrium level.
A cumulus cloud that is no longer dynamically connected with the atmospheric boundary layer via updrafts or downdrafts.
A low-level, horizontal, tube-shaped arcus cloud associated with a gust front of a convective storm or occasionally a cold front.
A low-level, horizontal, wedge-shaped arcus cloud associated with a convective storm's gust front.
A local, often abrupt lowering from a cumulonimbus cloud base into a low-hanging accessory cloud, normally a kilometer or more in diameter.
A type of fog caused by the advection of moist air over a cold surface, and the consequent cooling of that air to below its dewpoint.
Phenomenon particularly associated with smog episodes in cities such as Denver, Colorado.
Fog formed as a result of evaporation of water that is warmer than the air.
Water droplets suspended in the atmosphere in the vicinity the earth's surface that affect visibility.
A fog the droplets of which freeze upon contact with exposed objects and form a coating of rime and/or glaze.
Fog associated with frontal zones and frontal passages. It is usually divided into three types: warm-front prefrontal fog; cold-front post-frontal fog; and frontal-passage fog. The first two types are a result of rain falling into cold stable air and raising the dewpoint temperature. Frontal-passage fog can result from the ?mixing of warm and cold air masses in the frontal zone? or by ?sudden cooling of air over moist ground.?
A dense fog and/or drizzle from low stratus on the west coast of South America. It creates a raw, cold atmosphere that may last for weeks in winter and supplies a limited amount of moisture to the area.
1. According to U.S. weather observing practice, a fog that hides less than 0.6 of the sky and does not extend to the base of any clouds that may lie above it. As an obstruction to vision in an aviation weather observation, ground fog is encoded GF. 2. See radiation fog.
A name applied to a wet sea fog or very fine drizzle that drifts in from the sea in coastal districts of eastern Scotland and northeastern England. It occurs most frequently in summer.
Particles suspended, reducing visibility by scattering light; often a mixture of aerosols and photochemical smog.
In the US, the frequent fog on the slopes of the coastal mountains of California, especially applied when the fog overtops the range and extends as stratus over the leeward valleys.
A type of fog, composed of suspended particles of ice, partly ice crystals 20 to 100 m in diameter, but chiefly, especially when dense, droxtals 12?20 m in diameter. It occurs at very low temperatures, and usually in clear, calm weather in high latitudes. The sun is usually visible and may cause halo phenomena. Ice fog is rare at temperatures warmer than -30?C, and increases in frequency with decreasing temperature until it is almost always present at air temperatures of -45?C in the vicinity of a source of water vapor. Such sources are the open water of fast-flowing streams or of the sea, herds of animals, volcanoes, and especially products of combustion for heating or propulsion. At temperatures warmer than -30?C, these sources can cause steam fog of liquid water droplets, which may turn into ice fog when cooled (see frost smoke). See ice-crystal haze, arctic mist.
Fog, light and of short duration, produced by the mixing of two moist but nonsaturated air masses with different temperatures.
An advection fog produced as a monsoon circulation that transports warm moist air over a colder surface.
Fog formed by orographic lifting to condensation of moist air up a mountain slope.
A common type of fog, produced over a land area when radiational cooling reduces the air temperature to or below its dewpoint.
A haze created by the presence of finely divided particles of sea salt in the air, usually derived from the evaporation of sea spray.
Reduced visibility in the atmospheric boundary layer caused by suspended particles of soil, mixed into the air during strong winds.
A natural fog contaminated by industrial pollutants, a mixture of smoke and fog.
A type of fog formed when air flows upward over rising terrain and is, consequently, adiabatically cooled to or below its dewpoint.
Any nonoccluded front, or portion thereof, that moves so that the colder air replaces the warmer air; that is, the leading edge of a relatively cold air mass.
A low-level mesoscale boundary or transition zone hundreds of kilometers in length and up to tens of kilometers in width separating dry air from moist air.
The sector, in a horizontal plane, between the occluded front and a secondary cold-front of an occluded cyclone.
In meteorology, generally, the interface or transition zone between two air masses of different density
The forced ascent of the warmer, less dense air at and near a front, occurring whenever the relative velocities of the two air masses are such that they converge at the front.
Frontal surface above which air is descending.
A front (usually a cold front) at which the warm air descends the frontal surface (except, presumably, in the lowest layers).
A front that forms in the low pressure zone that covers the Mediterranean between the cold air over Europe and the warm air over the Sahara.
(Also called baiu front). A quasi-persistent, nearly stationary, east?west-oriented weak baroclinic zone in the lower troposphere that typically stretches from the east China coast, across Taiwan, and eastward into the Pacific, south of Japan. The term ?mei-yu? is the Chinese expression for ?plum rains.? The mei-yu front generally occurs from mid- to late spring through early to midsummer. This low-level baroclinic zone typically lies beneath a confluent jet entrance region aloft situated downstream of the Tibetan Plateau. The mei-yu/baiu front is very significant in the weather and climate of southeast Asia as it serves as the focus for persistent heavy convective rainfall associated with mesoscale convective complexes (MCCs) or mesoscale convective systems (MCSs) that propagate eastward along the baroclinic zone. The moisture source is typically the South China Sea and sometimes the Bay of Bengal. The usual lifting mechanism is low-level warm-air advection in association with a low-level jet on the equatorward flank of the baroclinic zone. Deep ascent and resulting organized MCCs/MCSs are especially favored when the low-level warm-air advection is situated beneath the favorable equatorward jet entrance region aloft.
A sharp horizontal temperature contrast of a few degrees Celsius within a width of tens of centimeters to a few meters along the trailing edge of a thermal plume in the surface layer of the atmospheric boundary layer.
An extension or protrusion of moist air into a region of lower moisture content. Cloudiness and precipitation are closely related to moist tongues.
A front that forms as a cyclone moves deeper into colder air.
A surface boundary formed by the horizontal spreading of thunderstorm-cooled air.
The horizontal discontinuity in temperature and humidity that marks the leading edge of the intrusion of cooler, more moist marine air associated with a sea breeze.
A special (and rare) case of the process of occlusion, where the point at which the cold front first overtakes the warm front (or quasi-stationary front) is at some distance from the apex of the wave cyclone.
A junction point within the tropics of three distinct air masses, considered to be an ideal point of origin for a tropical cyclone.
That area, within the circulation of a wave cyclone, where the warm air is found. Traditionally, it lies between the cold front and warm front of the storm; in the typical case, the warm sector continually diminishes in size and ultimately disappears (at the surface) as the result of occlusion.
A rare and randomly occurring bright ball of light observed floating or moving through the atmosphere close to the ground.
A particular aspect of a normal lightning flash occasionally seen when the observer happens to view end-on a number of segments of the irregular channel (zigzag lightning) and hence receives an impression of higher luminosity at a series of locations along the channel.
Weakly luminous upward propagating discharges, blue in color, emanating from the tops of thunderstorms.
The process by which negative charge centers at successively more distant locations in a thundercloud are tapped for discharge by successive strokes of cloud-to-ground lightning.
Lightning is a transient, high-current electric discharge with pathlengths measured in kilometers. The most common source of lightning is the electric charge separated in ordinary thunderstorm clouds.
The intense luminosity that propagates upward from earth to cloud base in the last phase of each lightning stroke of a cloud-to-ground discharge.
The sound emitted by rapidly expanding gases along the channel of a lightning discharge.
In popular terminology, any sudden and heavy fall of rain, almost always of the shower type.
Very small, numerous, and uniformly distributed water drops that may appear to float while following air currents.
A squall or thunderstorm in the Mediterranean.
A sequence of long-lived tornadoes produced by a cyclic supercell storm. Tornadoes touch down at quasi-regular intervals (typically 45 min). Usually a new tornado develops in a new mesocyclone just after an old tornado has decayed in an old, occluded neighboring mesocyclone. Sometimes, two successive tornadoes may overlap in time for a few minutes. The two mesocyclones may rotate partially around each other. If the damage tracks of the tornadoes appear to form a wavy broken line, the family is classified as a series mode. In the more common parallel-mode family, the damage tracks are parallel arcs with each new tornado forming on the right side of its predecessor. The parallel mode is subcategorized into left turn and right turn, according to the direction in which the paths curve.
Rain that falls in liquid form but freezes upon impact to form a coating of glaze upon the ground and on exposed objects.
A sudden squall of rain or sleet in England.
Any disturbed state of the atmosphere, especially as affecting the earth's surface, implying inclement and possibly destructive weather.
Any thunderstorm that is perceived by observers to be green. The perceptually dominant wavelength of light from green thunderstorms ranges from blue- green to yellow-green. The purity of the color is generally low and the topical mechanism that causes the green appearance is not understood. Although green clouds often occur in conjunction with severe weather, there is no evidence to support anecdotal attributions of the cause of this green to specific characteristics of severe storms, such as hail or tornadoes.
Precipitation in the form of balls or irregular lumps of ice, always produced by convective clouds, nearly always cumulonimbus. An individual unit of hail is called a hailstone. By convention, hail has a diameter of 5 mm or more, while smaller particles of similar origin, formerly called small hail, may be classed as either ice pellets or snow pellets. Thunderstorms that are characterized by strong updrafts, large liquid water contents, large cloud-drop sizes, and great vertical height are favorable to hail formation. The destructive effects of hailstorms upon plant and animal life, buildings and property, and aircraft in flight render them a prime object of weather modification studies. In aviation weather observations, hail is encoded A.
Any storm that produces hailstones that fall to the ground; usually used when the amount or size of the hail is considered significant.
In popular terminology, a thunderstorm of the air mass type that develops near the end of a hot, humid summer day; this term has no precise technical meaning.
Rain with a rate of accumulation exceeding a specific value that is geographically dependent.
Generally, a thunderstorm based at a comparatively high altitude in the atmosphere, roughly 2400 m or higher. These storms form most strikingly over arid regions, and frequently their precipitation is evaporated before reaching the earth's surface.
A hurricane radar band of circular or spiral shape associated with a tropical cyclone (hurricane or typhoon). Made evident by radar observations, hurricane bands typically curve cyclonically inward toward the center of the storm. The bands may be classified as primary if they merge into the eyewall encircling the eye of the storm, or secondary if they are disconnected from the eyewall. Hurricane bands generally move slowly around the center of the storm in the direction of the hurricane circulation. See banded structure.
A storm characterized by a fall of freezing liquid precipitation. The attendant formation of glaze on terrestrial objects creates many hazards.
In Scotland, a heavy fall of snow.
In England, a heavy fall of rain.
Generally, the effect of any lake in modifying the weather about its shore and for some distance downwind. This term is applied specifically to the region about the Great Lakes or the Great Salt Lake. More specifically, lake effect often refers to the generation of sometimes spectacular snowfall amounts to the lee of the Great Lakes as cold air passes over the lake surface, extracting heat and moisture, resulting in cloud formation and snowfall downwind of the lake shore.
Localized, convective snow bands that occur in the lee of lakes when relatively cold airflows over warm water. In the US this phenomenon is most noted along the south and east shores of the Great Lakes during arctic cold-air outbreaks. Snowstorm occurring near or downwind from the shore of a lake resulting from the warming (destabilization) and moistening of relatively cold air during passage over a warm body of water.
(Also called lamb-blasts, lamb-showers, lamb storm.) A slight fall of snow in the spring in England.
In England, a heavy fall of rain, accompanied by a high wind.
(Rare.) A tornado. 2. Colloquial expression describing tornadoes occurring with a parent cloud in its growth stage and with its vorticity originating in the boundary layer.
A storm of mesometeorological scale; thus, thunderstorms, squalls, and tornadoes are often put in this category.
The Doppler velocity pattern of a mesocyclone within a severe thunderstorm. In a storm-relative reference frame, the idealized signature is symmetric about the radar viewing direction with marked azimuthal shear across the core region between peak Doppler velocity values of opposite sign. Typical signatures consist of Doppler velocity differences of 25? 75 m s-1 across core diameters of 2?8 km, with resulting azimuthal shear values of 5 ? 10-3 s-1 to 2 ? 10-2 s-1.
A convective storm system usually composed of a cluster of ordinary convective cells at various stages of their life cycle. New cells within the convective system are generated primarily by either low-level convergence along a preexisting boundary, or by lifting at the leading edge of the system-scale cold pool that was produced by the previous cells. A multicell storm may have a lifetime of several hours, and may also have supercells incorporated as a part of the system as well. See also cell, ordinary cell, supercell, thunderstorm.
A tornado that occurs with a parent cloud in its growth stage and with its vorticity originating in the boundary layer. The parent cloud does not contain a preexisting midlevel mesocyclone. Landspouts and gustnadoes are examples of the nonsupercell tornado.
A cyclonic storm off the east coast of North America, so called because the winds over the coastal area are from the northeast.
An airmass thunderstorm that forms rapidly in an otherwise rain-free environment. This most often occurs on warm, humid days, in unstable meteorological conditions.
A squall line less than about 100 km ahead of a cold front, in the warm sector, having an orientation more or less parallel to the cold front.
The complete cloud and precipitation structure associated with an area of rainfall sufficiently elongated that an orientation can be assigned.
The process by which a single convective cell splits into two supercells, one dominated by cyclonic rotation and the other by anticyclonic rotation, their paths then deviating substantially from each other and other nearby convective cells.
A line of active thunderstorms, either continuous or with breaks, including contiguous precipitation areas resulting from the existence of the thunderstorms.
1. In general, any tornado over a body of water. 2. In its most common form, a nonsupercell tornado over water.
A bow-shaped line of convective cells that is often associated with swaths of damaging straight-line winds and small tornadoes.
An organized unit of convection within a convecting layer. It is isolated by a stream surface, with ascending motion in the center and descending motion near the periphery, or vice versa.
A cold low that has grown out of a trough and become displaced out of the basic westerly current and lies equatorward of this current.
A physical process at the initial stage of cyclone life cycle
A decrease in the central pressure of a pressure system as depicted on a constant- height chart, or an analogous decrease in height on a constant-pressure chart; the opposite of filling.
Convection that originates from an atmospheric layer above the boundary layer.
Any cyclonic-scale storm that is not a tropical cyclone, usually referring only to the migratory frontal cyclones of middle and high latitudes.
A point of maximum decrease in atmospheric pressure over a specified interval of time; on synoptic charts, a point of greatest negative pressure tendency; opposed to a pressure- rise center.
Region of convergence, often a line, downwind of a mountain or mountain ridge during fair-weather daytime conditions that are favorable for the formation of thermally forced upslope flow and deep convective mixing. Convergence forms between upslope (or sometimes light and variable) flow at lower elevations of the lee slopes and downslope flow at higher elevations, which results from the downward convective mixing of ambient momentum from the flow above ridgetops. With moist upslope flow and favorable conditions, updrafts produced by the convergence can lead to mountain cumulus formation, or trigger thunderstorm or severe weather activity.
A mesoscale zone of anticyclonically turning winds that develops downstream of the Cheyenne Ridge in northeast Colorado and southeast Wyoming, and is often centered just east of the foothills of the Rocky Mountains near the town of Longmont, Colorado. The cause of the feature is the interaction of the ambient low level northwest flow with the east?west terrain feature known as the Cheyenne Ridge. See also Denver convergence?vorticity zone.
An anticyclonically rotating vortex, around 210 km in diameter, in a convective storm.
A cyclonically rotating vortex, around 2?10 km in diameter, in a convective storm. The vorticity associated with a mesocyclone is often on the order of 10-2 s-1 or greater. (It should be noted that a mesocyclone is not just any cyclone on the mesoscale; it refers specifically to cyclones within convective storms.) Mesocyclones are frequently found in conjunction with updrafts in supercells. Tornadoes sometimes form in mesocyclones. Persistent mesocyclones that have significant vertical extent are detected by Doppler radar as mesocyclone signatures. Tornado warnings may be issued when a mesocyclone signature is detected.
A low pressure area on the mesoscale. It has been used to refer both to features observed within convective storms and features even larger in scale.
A regular pattern of convective cells that can develop in an atmospheric boundary layer heated from below or radiatively cooled from cloud top. This phenomenon is readily observed in satellite imagery during cold air outbreaks when continental air passes over the relatively warm coastal ocean. Cloud lines, marking horizontal roll vortices, form initially in the developing marine atmospheric boundary layer. These lines evolve into open cells, which are defined by clouds in the upward motion along the edges of honeycomb- shaped cells, with less cloudy subsiding air in their centers. The convective structure further evolves into closed cells, which have cloudy centers and cloud-free edges.
A subset of mesoscale convective systems (MCS) that exhibit a large, circular (as observed by satellite), long-lived, cold cloud shield. Alternatively, a dynamical definition of an MCC requires that the system have a Rossby number of order 1 and exhibit a horizontal scale comparable to the Rossby radius of deformation. In midlatitude MCS environments, the Rossby radius of deformation is about 300 km.
A cloud system that occurs in connection with an ensemble of thunderstorms and produces a contiguous precipitation area on the order of 100 km or more in horizontal scale in at least one direction. An MCS exhibits deep, moist convective overturning contiguous with or embedded within a mesoscale vertical circulation that is at least partially driven by the convective overturning.
Convective storm that contains similar radar characteristics to those of a supercell (e.g., hook echo, WER, BWER), but is significantly smaller in height and width. The diameter of the radar-detected rotation is 1?8 km. This is a relatively new storm type, the existence of which has been confirmed by data from the recently installed WSR?88D radars in the US. Mini-supercells occur in areas where the height of the equilibrium level is low, most often in the northern US, but possibly under certain weather conditions in any area of the world. They are sometimes found in landfalling tropical cyclones.
A ridge of smaller scale than a long-wave ridge. It ordinarily moves rapidly and is associated with a migratory anticyclonic disturbance in the lower troposphere. See short wave.
A pressure trough of smaller scale than a long-wave trough. It ordinarily moves rapidly and is associated with a migratory cyclonic disturbance in the lower troposphere. See short wave.
Atmospheric convection in which the phase changes of water play an appreciable role. All cumuliform clouds are manifestations of moist convection. The enthalpy exchange between condensing water vapor or freezing liquid water and air (see latent heat) is a major contributor to the positive buoyancy of updrafts, while the reverse exchange between air and evaporating water or melting ice contributes strongly to the negative buoyancy of downdrafts.
A depression that forms within the monsoon trough. The term is most frequently used to describe weak cyclonic disturbances that form over the Bay of Bengal and generally track northwestward over the Indian subcontinent. These occasionally intensify into tropical cyclones if they remain over warm ocean water long enough. The term is also used to describe depressions that form within the monsoon trough near Australia and in the western North Pacific region. The term has gained ascendancy in use to refer to a broad tropical cyclonic vortex characterized by 1) its large size, where the outermost closed isobar may have a diameter on the order of 600 n mi (1000 km); 2) a loosely organized cluster of deep convective elements, which may form an elongated band of deep convection in the east semicircle; 3) a low- level wind distribution that features a 100 n mi (200 km) diameter light-wind core, which may be surrounded by a band of gales or contain a highly asymmetric wind field; and 4) a lack of a distinct cloud system center. Most monsoon depressions that develop in the western North Pacific eventually acquire persistent central convection and accelerated core winds, marking their transitions into conventional tropical cyclones.
A convection of the summer monsoon circulation of the western North Pacific characterized by 1) a very large nearly circular low-level cyclonic vortex (not the result of the expanding wind field of a preexisting monsoon depression or tropical cyclone) that has an outermost closed isobar with a diameter on the order of 1200 n mi (2500 km); 2) a cloud band bordering the southern through eastern periphery of the vortex/surface low; and 3) a relatively long (two week) life span. Initially, a subsequent regime exists in its core and western and northwestern quadrants with light winds and scattered low cumulus clouds; later, the area within the outer closed isobar may fill with deep convective cloud and become a isobar or tropical cyclone. Note: a series of midget tropical cyclones may emerge from the ?head? or leading edge of the peripheral tropical cyclone of a monsoon gyre.
A seasonal low found over a continent in the summer and over the adjacent sea in the winter. Examples are the lows over the southwestern US and India in summer and those located off lower California and in the Bay of Bengal in winter. Palmer (1951) points out that, while the winter and summer monsoon lows appear similar on mean charts, they are dynamically quite different. Compare thermal low.
Long narrow sheets of warm air rising from a heated surface.
Occurrence of fog or haze in which considerable amounts of acidic material have been taken up from the gas phase, resulting in pH values less than approximately 3 in the liquid phase.
A popular expression for the deposition by rainfall of various airborne pollutants (especially SO2 and NO2) that have harmful effects on vegetation, soils, buildings and other external structures.
Removal of pollutants out of the top of the atmospheric boundary layer through the mixed-layer capping inversion. Normally pollutants cannot escape through the capping inversion. However, penetrating cumulus clouds, thunderstorms, mountain circulations, and frontal circulations can force polluted air through the inversion to vent pollutants into the free atmosphere.
Water vapor that removes particulate matter from the atmosphere
Removal of pollutants from the air by either rain or snow. Rainout (or snowout), which is the in-cloud capture of particulates as condensation nuclei, is one form of scavenging.
The removal of atmospheric gases or particles through their incorporation into hydrometeors, which are then lost by precipitation.
The vector difference between the real (or observed) wind and the geostrophic wind
When dust, sand, snow, and/or spray is raised by the wind to a height of 6 feet or more
A widespread convectively induced straight-line windstorm.
Small-scale downward moving air current in a cumulonimbus cloud.
In the classification of Jeffreys, a wind motion only in response to the pressure force.
1. A sudden, brief increase in the speed of the wind. It is of a more transient character than a squall and is followed by a lull or slackening in the wind speed. Generally, winds are least gusty over large water surfaces and most gusty over rough land and near high buildings. According to U.S. weather observing practice, gusts are reported when the peak wind speed reaches at least 16 knots and the variation in wind speed between the peaks and lulls is at least 9 knots. The duration of a gust is usually less than 20 s. 2. With respect to aircraft turbulence, a sharp change in wind speed relative to the aircraft; a sudden increase in airspeed due to fluctuations in the airflow, resulting in increased structural stresses upon the aircraft. 3. (Rare.) Same as cloudburst.
A wind that opposes the intended progress of an exposed, moving object, for example, rendering an airborne object's airspeed greater than its groundspeed; the opposite of a tailwind.
General term for winds characterized by intense heat and low relative humidity, such as summertime desert winds or an extreme foehn.
A local wind created by acceleration of the airflow through a gap, constriction, or channel in a mountain range or between ranges.
The region of a jet stream axis with the greatest winds.
Relatively strong winds concentrated within a narrow stream in the atmosphere.
The axis of maximum wind speed in a jet stream.
1. Winds that, over a small area, differ from those that would be appropriate to the general large-scale pressure distribution, or that possess some other peculiarity. Often these winds have names unique to the area where they occur. Local winds may be classified into three main groups. The first includes diurnally varying airflows that are driven by local gradients of surface heat flux (e.g., near the shore of a sea or lake) or by diurnal heating or cooling of the ground surface in areas of sloping or mountainous terrain. These include land and sea breezes, mountain?valley circulations, and drainage and slope winds. The second group consists of winds produced by the interaction of a synoptic-scale flow with orography. These may be further subdivided into barrier jets, gap winds, downslope windstorms, and include such local phenomena as the tehuantepecer, Santa Ana, foehn, mistral, and bora. The third group includes those winds accompanying convective activity, more specifically individual thunderstorms or mesoscale convective systems. These are generally the surface manifestations of precipitation- cooled diverging outflow and in some locations are given special names due to the distinctive character of the weather associated with them (e.g., the haboob). 2. Local or colloquial names given to frequently occurring or particularly noteworthy winds (sometimes because of the bad weather associated with them), usually from a certain direction. Often these names reflect the direction from which the wind comes (e.g., sou'wester, nor'easter).
The wind or wind component along the local meridian, as distinguished from the zonal wind. In a horizontal coordinate system fixed locally with the x axis directed eastward and the y axis northward, the meridional wind is positive if from the south, and negative if from the north.
A wind that assists the intended progress of an exposed, moving object, for example, rendering an airborne object's groundspeed greater than its airspeed; the opposite of a headwind.
The generally small, localized atmospheric circulations.
The mean wind-shear vector in geostrophic balance with the gradient of mean temperature of a layer bounded by two isobaric surfaces.
The wind system, occupying most of the Tropics, that blows from the subtropical highs toward the equatorial trough; a major component of the general circulation of the atmosphere.
In the Northern Hemisphere, a wind that rotates in a clockwise direction with increasing height; the opposite of backing wind.
A zonal circulation of the atmosphere confined to equatorial regions and driven principally by the oceanic temperature gradient. In the Pacific, air flows westward from the colder, eastern area to the warm, western ocean, where it acquires warmth and moisture and subsequently rises. A return flow aloft and subsidence over the eastern ocean complete the cell
In meteorology, the flow of air along a latitude circle; more specifically, the latitudinal (east or west) component of existing flow.
In mountain meteorology, an upslope wind driven by heating (usually daytime insolation) at the slope surface under fair-weather conditions.
A jet on the windward side of a mountain barrier, blowing parallel to the barrier.
A squall accompanied by dark clouds and generally by heavy rain.
Mesoscale vortices observed at the ends of a line segment of convective cells, usually cyclonic on the northern end of the system and anticyclonic on the southern end, for an environment of westerly vertical wind shear
A fall wind with a source so cold that, when the air reaches the lowlands or coast, the dynamic warming is insufficient to raise the air temperature to the normal level for the region; hence it appears as a cold wind
The mountain wind of a canyon, that is, the nighttime down-canyon flow of air caused by cooling at the canyon walls.
An east or southeast desert wind in Morocco (North Africa), especially in the north.
The name given to the foehn in western North America, especially on the plains to the lee or eastern side of the Rocky Mountains in the US and Canada.
A wind blowing from the desert.
A wind directed down a slope, often used to describe winds produced by processes larger in scale than the slope.
A very strong, usually gusty, and occasionally, violent wind that blows down the lee slope of a mountain range, often reaching its peak strength near the foot of the mountains and weakening rapidly father away from the mountains.
A wind that accelerates as it moves downslope because of its low temperature and greater density.
A warm, dry, downslope wind descending the lee side of the Alps as a result of synoptic-scale, cross-barrier flow over the mountain range.
The humid east wind that crosses the divide of the Andes east of Lake Titicaca and descends on the west in violent squalls; probably the same as puelche.
A sea breeze of Naples in Italy.
A squally northwesterly wind, cold, humid, and showery, that occurs in the rear of a low pressure area over the English Channel and off the Atlantic coast of France and northern Spain.
A strong, low-level wind through either a relatively level channel between two mountain ranges or a gap in a mountain barrier; originally applied to strong (10?20 m s-1) easterly winds through the Strait of Juan de Fuca between the Olympic Mountains of western Washington State and the mountains of Vancouver Island, British Columbia, Canada. There they have been defined as ?a flow of air in a sea level channel that accelerates under the influence of a pressure gradient parallel to the axis of the channel.? As in the case of mountain- gap winds, this term has also been applied to pressure-gradient winds accelerating through a gap in a mountain barrier. The pressure gradient often results from a stable, post-cold-frontal anticyclone approaching the barrier and being partially blocked (see blocking) as it ascends the barrier, except for the flow through the gap or channel. The tehuantepecer of Central America is a well- known gap wind by this definition. These flows have sometimes been referred to as jet-effect wind and canyon wind.
A sea breeze. In southwest France it refers to a southwesterly sea breeze that sets in about 9 A.M., reaches it maximum towards 2 P.M. and ceases about 5 P.M.
A local dry wind in the northern plains of Java, resembling the foehn. It is caused by a wind crossing the mountains near the south coast and pushing between the volcanoes.
A fresh westerly wind of oceanic origin in Morocco.
Hard squalls from the northeast in Libya and Africa. They are sudden and frequent and are accompanied by heavy rain and thunder.
A hot dust-bearing desert wind in Tripolitania (northwestern Libya), similar to the foehn.
A shallow gravity wind, along the icy surface of a glacier, caused by the temperature difference between the air in contact with the glacier and free air at the same altitude. The glacier wind does not reverse itself diurnally as do mountain and valley winds, but it reaches its maximum intensity in the early afternoon. The glacier wind is characterized by strongly turbulent flow. See katabatic wind.
A gap wind or canyon wind through a gorge.
A wind resulting from cold air running or flowing down a slope, caused by greater air density near the slope than at the same altitude some distance horizontally from the slope.
An Italian name for the northeast wind. It was given by Roman sailors to the northeast wind in the Gulf of Lions because it came from the direction of the Greek colony of Marsala (Marseilles). Wind names of similar origin are common in the western Mediterranean, for example, gregale.
The Maltese and best-known variant of a term for a strong northeast wind in the central and western Mediterranean and adjacent European land areas (stronger than the levante).
In the Tirol, an east wind during March and April.
A nautical term for a violent squall of wind from mountain ravines on the Pacific side of Central America.
A strong wind and sandstorm or duststorm in northern and central Sudan, especially around Khartoum, where the average number is about 24 a year. The name comes from the Arabic word habb, meaning ?wind.? Haboobs are most frequent from May through September, especially in June, but they have occurred in every month except November. Their average duration is three hours; they are most severe in April and May when the soil is driest. They may approach from any direction, but most commonly from the north in winter and from the south, southeast, or east in summer. The average maximum wind velocity is over 13 m s-1 (30 mph) and a speed of 28 m s-1 (62 mph) has been recorded. The sand and dust form a dense whirling wall that may be 1000 m (3000 ft) high; it is often preceded by isolated dust whirls. During these storms, enormous quantities of sand are deposited. Haboobs usually occur after a few days of rising temperature and falling pressure.
A local strong wind that blows through the Dzungarian Gate (in western China), a gap in the mountain ridge separating the depression of Lakes Balkash and Ala Kul from that of Lake Ebi Nor. The wind resembles the foehn and brings a sudden rise of temperature, in winter from about -26? to about -1?C.
A circulation similar to a sea breeze, except not at a shore. The inland sea breeze is a very weak thermal circulation caused by temperature contrast between different land surfaces and is sometimes observed between cool irrigated farm land and neighboring dry desert land. This phenomenon is observed only when the synoptic-scale winds are very light.
A hot, dry, west or southwest wind of foehn type in the lee of the Sri Lanka hills during the southwest monsoon in June and July.
In India, a short-lived dusty squall at the onset of the southwest monsoon (April? June) in Bengal.
A violent northeast wind of Central Asia occurring during spring and summer.
On the Bulgarian coast, a west wind that usually follows rain and persists for one to three days.
A violent east wind on Lake Tanganyika in Africa.
A strong southwest wind on the southern shore of the Gulf of Aden, especially at Berbera, Somaliland, during the southwest monsoon.
Most widely used in mountain meteorology to denote a downslope flow driven by cooling at the slope surface during periods of light larger-scale winds; the nocturnal component of the along-slope wind systems.
A moderate to gale-force southeasterly wind in the Persian Gulf; it is accompanied by gloomy weather, rain, and squalls.
(Also spelled camsin, chamsin, kamsin, khamasseen, khemsin.) A dry, dusty, and generally hot desert wind in Egypt and over the Red Sea. It is generally southerly or southeasterly, occurring in front of depressions moving eastward across North Africa or the southeastern Mediterranean. The deep khamsins occur in spring with depressions traveling east-northeast across the northern Sahara. They are preceded by a heat wave lasting about three days and are followed by a duststorm. The passage of the depression is marked by a cold front bringing Mediterranean air and a sudden drop in temperature. See ghibli, chili, sirocco.
A cold southwest wind of Simons Bay, South Africa.
Local name for a strong southeast wind in the vicinity of Palmer in the Matanuska Valley of Alaska. The knik wind blows most frequently in the winter, although it may occur at any time of year. In winter the knik winds are accompanied by very pronounced temperature rises; cases of more than 10?C in 24 hours have been observed. These winds may last from one to ten days. They result from a pressure gradient normal to the Chugach Mountains, causing a pronounced foehn effect in the Matanuska Valley.
A dry foehnlike wind from southeast or south in Cheribon and Tegal in Indonesia. It is caused by the east monsoon that develops a jet effect in passing through the gaps in the mountain ranges and descends on the leeward side.
A stormy, rain-bringing wind from the southwest or south-southwest in Hawaii. It blows about five times a year on the southwest slopes that are in the lee of the prevailing northeast trade winds. Kona is the Polynesian word for ?leeward.? It is associated with a southward or a southeastward swing of the Aleutian low and the passage of a secondary depression (kona cyclone) from northwest to southeast, north of the islands.
(Also spelled kosava, koschawa.) A cold, very squally wind, descending from the east or southeast in the region of the Danube ?Iron Gate? through the Carpathians, continuing westward over Belgrade, thence spreading northward to the Rumanian and Hungarian borderlands and southward as far as Nish. In winter it brings temperatures down to below -29C and it is cool even in summer, when it is also dusty. It usually occurs with a depression over the Adriatic and high pressure over southern Russia, a frequent situation in winter. It is usually explained as a jet-effect wind through the Iron Gate, giving speeds well above the gradient wind, but it can be regarded as a katabatic wind intermediate between foehn and bora. The kossava has a marked diurnal variation, with its maximum occurring between 5 AM and 10 AM.
(Also spelled Krakatau; formerly called overtrades.) A layer of easterly winds over the Tropics at an altitude of about 18-24 km. This layer tops the midtropospheric westerlies (the antitrades), is at least 6 km deep, and is based at about 2 km above the tropopause. This easterly current is more prominent and better defined in the summer hemisphere. It derives its name from the observed behavior of the volcanic dust carried around the world after the great eruption of Krakatoa (6?S, 105?E) in 1883.
A moderate to strong southwest wind in Provence (southeastern France), mild, humid, and very cloudy or rainy. On the coast it raises a rough sea. It is not frequent, occurring only in March. In the Swiss? French Alps it is locally termed labech, and is squally with thunder, hail, and brief torrential downpours; it comes mainly in autumn and winter.
Severe squalls during the change of seasons in October and November in Arabia.
A wind, similar in origin to the sea breeze but generally weaker, blowing from the surface of a large lake onto the shores during the afternoon; it is caused by the difference in surface temperature of land and water as in the land and sea breeze system. In addition to area, the depth of the lake is an important factor; a shallow lake warms up rapidly and is less effective as the source of a lake breeze in summer than is a deep lake. Lake breezes are well developed around the Great Lakes of North America, where they temper the summer heat.
A coastal breeze blowing from land to sea, caused by the temperature difference when the sea surface is warmer than the adjacent land. Therefore, it usually blows by night and alternates with sea breeze, which blows in the opposite direction by day. See puelche, karif.
Spanish nautical term for east wind. The name is given to a hot, dry, dusty easterly, or southeasterly wind that blows from the Atlantic coast of Morocco out to Madeira and the Canary Islands. It is a form of sirocco and occurs in front of depressions advancing eastward. Compare levanto.
The Spanish and most widely used term for an east or northeast wind occurring along the coast and inland from southern France to the Straits of Gibraltar. It is moderate or fresh (not as strong as the gregale), mild, very humid, overcast, and rainy; it occurs with a depression over the western Mediterranean Sea. In summer it is rare and weak; in January it is inhibited by the Iberian anticyclone. It is most frequent from February to May and October to December. A levant (French spelling) with fine weather is a levant blanc; in the Roussillon region of southern France (where, as along the Catalonian coast of Spain, it is called llevant) it often brings floods in the mountain streams. The levanter of the Gibraltar Straits is a related phenomenon. Compare leste, lombarde, levantera.
A persistent east wind in the Adriatic, usually bringing cloudy weather.
A hot, sand- and dust-laden wind from between southeast and southwest that blows in front of a depression on the southeast coast of Spain but extends only a few miles inland.
Italian name for a southwest wind; used especially in northern Corsica for the west or southwest wind that blows throughout the year, and especially in winter when it is often stormy. On windward slopes it brings rain, with thunderstorms in summer and autumn. After crossing the mountains it is warm and dry, but may be very turbulent.
A name sometimes given the west wind through the Straits of Gibraltar.
A squall that occurs along a squall line. This term is now confined mostly to nautical usage.
An easterly wind (from Lombardy) that predominates along the French?Italian frontier. It comes from the High Alps. In winter it is violent and forms snowdrifts in the mountain valleys. In the plains it is gentle and very dry. It is associated with an anticyclone over France and central Europe, or with high pressure to the southeast of Europe and low pressure to the northwest along with falling pressure over western France.
1. A damp unpleasant wind that blows from the south in Madras (India). 2. A wind from the northeast at night in Sri Lanka.
(Also called mackerel gale.) A wind that ruffles the water, favoring the catching of mackerel.
Same as a mackerel breeze
A northwesterly wind with fine weather that blows, especially in summer, in the Adriatic; it is most frequent on the western shore and is equivalent to the etesians of the eastern Mediterranean. It is also found on the coasts of Corsica and Sardinia. Compare mistral.
A wind, named after the Maloja Pass between the Engadine and Bergall, Switzerland, that blows down the valley of the Upper Engadine by day and either up or down by night. This deviation from the usual nature of mountain and valley winds is attributed to the fact that the stronger daytime valley wind from the south overtops the ridge and continues down the Engadine.
(Also called mamaliti, mamatili.) A light northwest wind of Sicily; a form of mistral.
A warm moist southeast wind from the sea on the French Mediterranean coast and in the Maritime Alps, especially frequent in spring and autumn. In the Rh?ne delta it blows also from the south. The marin is associated with depressions that cross southern France or northern Spain and the Gulf of Lions. Generally, it is strong and regular, sometimes violent and turbulent in hilly country as the ayalas in the Massif Central; it is very humid, cloudy with hill fog, and often rainy (unless unaccompanied by fronts, when it is the marin blanc). The heavy rains, which may continue for one or two days on the mountain slopes, cause dangerous river floods. On the western slope of the C?vennes it becomes the autan. In the southern C?vennes the marin is called the aygalas. On the coast of Catalonia (northeast Spain) and Roussillon (southern France) it is the marinada and generally occurs with a depression centered over or south of the Gulf of Gascony. Compare sirocco.
The local name, taken from the Matanuska River, for a strong, gusty, northeast wind that occasionally occurs during the winter in the vicinity of Palmer, Alaska.
The morning wind, that is, an east wind. In the Morvan Mountains and the center of the Massif Central in France, the matinal often blows for several days, especially in summer, and brings fine weather. On winter mornings a northeast or east wind descends the western slopes of the Alps (where it is known as the matini?re) bringing cold and generally fine weather. Compare solaire.
1. (Also spelled melt?mi.) A strong wind from the northeast or east that often sets in suddenly and blows during the day in summer on the Bulgarian coast and in the Bosporus. 2. Same as monsoon.
Northwest wind on Lake Maggiore, Italy.
A mesoscale wind maximum. It typically may have an along-flow length scale of tens to hundreds of kilometers and a cross- flow length scale of 100 km. Mesojets differ from planetary-scale jets, which can have length scales of several thousand kilometers, and synoptic-scale jets, which may have length scales of 1000? 2000 km and are commonly found in association with progressive synoptic-scale troughs and ridges. Larger mesojets may also sometimes be known as jet streaks. Mesojets can form adjacent to prominent orographic features in association with terrain-channeled flow. Mesojets are also seen in association with organized mesocale convective systems as typified by the evaporatively driven rear-inflow jet commonly found behind active squall lines lines. Mesojets may also be found in conjunction with prominent lower-tropospheric stable layers where the airflow can become decoupled from the planetary boundary layer, especially at night. An exceptionally well organized lower-tropospheric mesojet extending over hundreds of kilometers might be known as a low-level jet.
A warm, moist sea breeze from the south that sets in at midday in Provence, France, south of Mount Ventoux. In the Roussillon region the midday south wind (mitgjorn) is irregular and generally light, and is dry after crossing the Pyrenees.
The strong wind blowing across a mountain crest, responsible for the formation of the Moazagotl cloud.
Breeze blowing from Arve toward Geneva in Switzerland.
The temporary extension of deep monsoon flow into a region not normally dominated by persistent monsoon flow. This temporary extension or surge may last from a few days to three weeks. These surges most commonly occur eastward across the Philippine Sea into the western North Pacific and east of Australia into the western South Pacific. The establishment of a reverse-oriented monsoon trough is accompanied by an eastward surge in the monsoon flow. Monsoon surges are often precursors to the development of tropical cyclones.
The night land breeze on Lake Geneva, Switzerland. It blows from the north from 5-7 P.M. until 7-9 A.M. as a poweful breeze. In the late fall and winter it blows almost throughout the day.
A nocturnal component of the mountain?plains or mountain?valley wind systems encountered during periods of light synoptic flow.
A local wind blowing through a gap between mountains, a gap wind. This term was introduced by R. S. Scorer (1952) for the surface winds blowing through the Strait of Gibraltar. When air stratification is stable, as it usually is in summer, the air tends to flow through the gap from high to low pressure, emerging as a ?jet? with large standing eddies in the lee of the gap. The excess of pressure on the upwind side is attributed to a pool of cold air held up by the mountains. Similar winds occur at other gaps in mountain ranges, such as the tehuantepecer and the jochwinde, and in long channels, such as the Strait of Juan de Fuca between the Olympic Mountains of Washington and Vancouver Island, British Columbia. Compare jet-effect wind, canyon wind, mountain wind.
The diurnal cycle of local winds between a mountain or a mountain range and the adjacent or surrounding plains during periods of weak synoptic flow.
The diurnal cycle of local winds in a mountain valley during clear or mostly clear periods of weak synoptic flow.
A nocturnal, thermally forced wind from the direction of the mountains, generated by cooling along the mountain slopes; a downvalley wind, or the nighttime downslope (katabatic) component of a mountain?plains wind system.
The Arabic name for a northeasterly wind that ocurrs in winter on the Iranian coast of the Persian Gulf, especially near the entrance to the gulf and also on the Makran coast.
(Also spelled narbon?.) In France, a wind coming from Narbonne; a north wind in the Roussillon region of southern France resembling the tramontana. If associated with an influx of arctic air, it may be very stormy with heavy falls of rain or snow. It is especially violent in the region of Perpignan where it blows in a succession of squalls for several days. In Provence it is rarer and blows from the west. In lower Languedoc and the southern C?vennes, the narbonnais is an infrequent, mild, moist, moderate southwest wind in winter and early spring, sometimes bringing thunderstorms.
Dry squalls that occur at night in southwest Africa and the Congo. It is likely that this term is loosely applied to other diurnal local winds such as mountain wind, land breeze, midnight wind, etc.
A strong, persistent northerly wind in the Philippines.
A northeast wind, particularly a strong wind or gale.
A northerly wind; in general, a cold windstorm from the north.
A northerly foehn wind blowing down the Italian side of the Alps. The northern slopes are normally cooler than the southern slopes, and the dynamic warming is often insufficient to overcome the difference of temperature. Hence a warm dry northerly wind of foehnlike character occurs less frequently than the south foehn.
(Often contracted nor'wester.) A northwesterly wind (as Canterbury northwester).
Wind blowing from land to sea. During synoptic conditions of light winds, offshore winds near the surface often occur at night as a component of the land breeze.
A wind blowing from water onto land; the wind may be a result of heating differences between land and water or related to synoptic weather patterns.
Nocturnal cold-air jet flowing out of the mouth of a valley or canyon as it opens onto a plain.
Strong straight-line winds associated with nontornadic outflow from strong thunderstorms.
A coastal local wind that blows from sea to land, caused by the temperature difference when the sea surface is colder than the adjacent land.
A strong wind characterized by a sudden onset, a duration of the order of minutes, and then a rather sudden decrease in speed.
The relatively cool pool of air that results when a thunderstorm downdraft reaches the earth's surface and spreads horizontally as a density current.
A wind directed up a slope, often used to describe winds produced by processes larger in scale than the slope.
A wind that ascends a mountain valley (upvalley wind) during the day; the daytime component of a mountain?valley wind system.
A strong, cold, dry, west wind of eastern Asia, especially northern China, that sweeps across the plains in winter carrying a fine yellow dust from the deserts.
Any soft, gentle breeze.
In epidemiology, an epidemic is a classification of a disease that appears as new cases in a given human population, during a given period, at a rate that substantially exceeds what is expected based on recent experience (the number of new cases in the population during a specified period of time is called the incidence rate).
Pollination is an important step in the reproduction of seed plants: the transfer of pollen grains (male gametes) to the plant carpel, the structure that contains the ovule (female gamete). The receptive part of the carpel is called a stigma in the flowers of angiosperms and a micropyle in gymnosperms. The study of pollination brings together many disciplines, such as botany, horticulture, entomology, and ecology. Pollination is important in horticulture because most plant fruits will not develop if the ovules are not fertilized. The pollination process as interaction between flower and vector was first addressed in the 18th century by Christian Konrad Sprengel.
Embedded in, carried by, or running through a glacier
Of streams, deposits, and other features, being immediately in front of or just beyond the outer limits of a glacier or ice sheet, and formed by or derived from glacier ice.
Pertaining to the area in or at the bottom of, or immediately beneath, a glacier.
A significant increase in sea surface temperature over the eastern and central equatorial Pacific that occurs at irregular intervals, generally ranging between two and seven years.
Biodiversity is the variation of life forms within a given ecosystem, biome or for the entire Earth. Biodiversity is often used as a measure of the health of biological systems.
The presence of substances in the atmosphere, particularly those that do not occur naturally
Habitat fragmentation is a process of environmental change important in evolution and conservation biology. As the name implies, it describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat). Habitat fragmentation can be caused by geological processes that slowly alter the layout of the physical environment or by human activity such as land conversion, which can alter the environment on a much faster time scale. The former is suspected of being one of the major causes of speciation. The latter is causative in extinctions of many species. Habitat fragmentation is frequently caused by humans when native vegetation is cleared for human activities such as agriculture, rural development or urbanization. Habitats which were once continuous become divided into separate fragments. After intensive clearing, the separate fragments tend to be very small islands isolated from each other by crop land, pasture, pavement, or even barren land. The latter is often the result of slash and burn farming in tropical forests. The term habitat fragmentation can be considered to include six discrete processes: Reduction in the total area of the habitat, increase in the amount of edge, decrease in the amount of interior habitat, isolation of one habitat fragment from other areas of habitat, breaking up of one patch of habitat into several smaller patches, and Decrease in the average size of each patch of habitat.
Type of air pollution, such as Los Angeles smog, associated with the buildup of oxidation products formed from the degradation of hydrocarbons, etc.
The movement of salt water into fresh water aquifers.
Process by which saline water underlying freshwater in an aquifer rises upward into the freshwater zone as a result of pumping water from the freshwater zone.
An atmospheric anticyclonic circulation, a closed circulation. The wind in an anticyclone is in the clockwise direction in the Northern Hemisphere and counterclockwise in the Southern Hemisphere.
In radar usage, a local maximum in radar reflectivity that undergoes a life cycle of growth and decay. The rising portion of the reflectivity maximum is indicative of updraft, and the later descending portion is indicative of a precipitation downdraft. Cells in ordinary convective storms last from 20 to 30 min, but often form longer-lasting multicell convective storms. Cells in supercell storms are more steady and last considerably longer. See also thunderstorm cell.
In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid flows past an obstacle. The moving fluid creates a space devoid of downstream-flowing water on the downstream side of the object. Fluid behind the obstacle flows into the void creating a swirl of fluid on each edge of the obstacle, followed by a short reverse flow of fluid behind the obstacle flowing upstream, toward the back of the obstacle. This phenomenon is most visible behind large emergent rocks in swift-flowing rivers.
An interfacial region in which flow is smooth and nonturbulent. Above a surface, a laminar layer will develop and fluid velocity will increase with distance from the surface, but not indefinitely. At some point, flow will become turbulent, with the laminar sublayer separating the turbulent layer from the surface. In the real world, most laminar boundary layers are extremely thin (order of 1 mm), but can be of biological importance, for example, next to plant leaves or as invertebrate refuges in streams.
(Also called sheet flow, streamline flow.) A flow regime in which fluid motion is smooth and orderly, and in which adjacent layers or laminas slip past each other with little mixing between them. Exchange of material across laminar layers occurs by molecular diffusion, a process about 106 times less effective than turbulence. Laminar flow can be easily predicted as velocity increases at a steady rate from a boundary. This contrasts with the chaotic and random nature of turbulent flow. Laminar flow is not a common occurrence in the statically neutral and unstable atmosphere and is confined to a very thin layer (1 mm) adjacent to very smooth surfaces such as snow and ice. However, in strongly statically stable regions such as the the nocturnal boundary layer, the Richardson number can be large enough that turbulence is suppressed, and the flow is laminar over a layer many tens of meters thick.
A layer in which the fluid undergoes smooth, nonturbulent flow. It is found between any surface and a turbulent layer above. See laminar boundary layer, laminar flow.
A straight line vortex, the flow of which can be modeled in two dimensions, with a point concentration of vorticity surrounded by irrotational flow.
In meteorology, an elongated area of relatively low atmospheric pressure; the opposite of a ridge.
In studies of the general circulation, the eddies are the departures of a field from the zonal mean of that field; the stationary eddies are the time-averaged, or time-invariant, component of the eddy field.
More often the term refers to a flow with closed streamlines or to the idealized case in which all vorticity is concentrated in a vortex filament.
state of a layer of atmosphere when it has superadiabatic lapse rate of temperature
The state of a layer of unsaturated air when its lapse rate of temperature is less than the dry-adiabatic lapse rate but greater than the moist-adiabatic lapse rate.
An instability due to the buoyancy force of heavy fluid over light fluid overcoming the stabilizing influence of viscous forces.
A temperature inversion (temperature rising with height) in the atmosphere, encountered upon vertical ascent through a sloping front (or frontal zone).
In meteorology, a departure from the usual decrease or increase with altitude of the value of an atmospheric quantity; also, the layer through which this departure occurs (the inversion layer), or the lowest altitude at which the departure is found (the base of the inversion).
An instability of the basic flow of an incompressible inviscid fluid in two parallel infinite streams of different velocities and densities.
The behavior of a fluid with a Reynolds number typically greater than 1E4 to 1E6, which usually occurs within the atmosphere. The main property of such flows is a constant friction stress within the surface layer that depends only on relative roughness but not on the Reynolds number itself. Thus, molecular viscosity and qualities occurring in flow descriptions that are dependent on the Reynolds number may be totally ignored.
Turbulence produced by shear flow.
The ability of a fluid at rest to become turbulent or laminar due to the effects of buoyancy.
Irregular fluctuations occurring in fluid motions.
The region of turbulence immediately to the rear of a solid body in motion relative to a fluid
The turbulent perturbations of temperature remaining in a stable boundary layer after all turbulent motions have died out.
The process of transport solely by the mass motion (velocity field); also, the rate of change of the value of the advected property at a given point.
That property of an object that enables it to float on the surface of a liquid, or ascend through and remain freely suspended in a compressible fluid such as the atmosphere.
In general, mass motions within a fluid resulting in transport and mixing of the properties of that fluid. Convection, along with conduction and radiation, is a principal means of energy transfer.
A buoyant jet stream in which the buoyancy is supplied steadily from a point source; the buoyant region is continuous.
Phenomena by which traces gases or particles are transferred from atmosphere to a surface.
A pattern of smokestack plume dispersion in a statically stable atmosphere, in which the plume spreads out in the horizontal like an oriental fan and meanders about at a fixed height with little vertical spread.
The phenomenon where the upper part of a smoke plume diffuses more rapidly upward than the bottom part diffuses downward. This generally occurs when the boundary layer near the ground is more stable than it is aloft. Compare coning, fanning, looping.
Buoyant jet in which the buoyancy is supplied from a point source; the buoyant region is continuous. 2. A mostly horizontal (sometimes initially vertical) stream of pollutant that is being blown downwind from a smokestack.
A form of convection driven by a combination of gravitational and centrifugal forces.
An effect due to heat sources within a local exhaust enclosure (stack) producing convective air currents with vertical velocities proportional to the rate of heat transferred to the surrounding air and to the height of rise of the heated air.
Advection of vorticity by the total wind or force.
The eastward flux of mass, momentum, heat, moisture or any other property of a fluid by mean motion or by correlation with the eastward component of motion, that is, eddy flux.
Fluvial is used in geography and earth science to refer to the processes associated with rivers and streams and the deposits and landforms created by them [Wikipedia]
One of 3 processes in the Rock Cycle. Igneous refers to the process whereby hot material from the mantle is squeezed upward toward the earth's surface. If it has not reached the surface then the material is described as an intrusive structure and the rocks it creates are called Intrusive Rock. If it extrudes from the surface the material is described as a volcano and the rock it creates is known as Extrusive Rock. [Wikipedia]
One of 3 processes in the Rock Cycle. When sedimentary (and/or) igneous layers are folded, bent or twisted by heat and pressure due to motions of tectonic plates or intrusions by magma, the rocky material is transformed into other rock called metamorphic rock. [Wikipedia]
The process in which mountains begin to collapse under their own weight and spread out laterally.
Orogeny refers to natural mountain building, and may be studied as (a) a tectonic structural event, (b) as a geographical event, and (c) a chronological event. Orogenic events (a) cause distinctive structural phenomena and related tectonic activity, (b) affect certain regions of rocks and crust, and (c) happen within a specific period of time. [Wikipedia]
The rock cycle is a fundamental concept that describes the dynamic transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous. [Wikipedia]
One of 3 processes in the Rock Cycle. When wind or water deposit fine grained material on the surface, it creates sheets. Over thousands of years, the composition can change subtly or distinctly and the result is differing compositions of layered deposits. As the overlying layers compact the soil underneath the soil is converted to rock by the process of lithification. [Wikipedia]
A substantial break or gap in the geologic record where a rock unit is overlain by another that is not next in stratigraphic sucession, such as an interruption in continuity of a depositional sequence of sedimentary rocks or a break between eroded igneous rocks and younger sedimentary strata. It results from a change that caused deposition to cease for a considerable time, and it normally implies uplift and erosion with loss of the previous formed record.
The Wilson cycle (a plate tectonics based rock cycle) was developed by J. Tuzo Wilson during the 1960s and 1970s. [Wikipedia]
A regional-scale low-angle normal fault.
Right-lateral separation sense; in plan view, the side opposite the observer appears displaced to the right.
A fault along which there is some separation parallel to the dip of the fault.
The net slip of the fault lies in the dip direction of the fault
A fault whose two sides have approached each other substantially in the direction perpendicular to the fault.
A large-displacement (kilometers or tens of kilometers) shallowly dipping to subhorizontal fault or shear zone.
The fault is horizontal
An extraction fault with some displacement within the fault plane.
The fault-parallel displacement is effectively zero, as in an extraction fault.
The hanging wall appears to have moved down relative to the footwall; dip of fault usually 45-90 degrees.
The net slip of the fault lies between the strike and dip directions of the fault; the slip vector rakes between 10 and 80 degrees in the plane of the fault.
An extraction fault with no discernible displacement within the fault plane.
The hanging wall appears to have moved down relative to the footwall; dip of fault usually greater than 45 degrees.
A fault on which there is increasing offset or separation along the strike from an initial point of no offset, with reverse offset in the opposite direction.
Left-lateral separation sense; in plan view, the side opposite the observer appears displaced to the right.
A fault along which there is some separation parallel to the strike of the fault.
The net slip of the fault (slip vector) is parallel to the strike of the fault.
Reverse fault with dip typically less than 45 degrees; horizontal compression, rather than vertical displacement is characteristic.
A regional-scale low-angle thrust fault.
A large scale strike-slip fault in which the fault surface is steeply inclined.
A variety of strike-slip fault along which the displacement suddenly stops or changes form; typically associated with mid-ocean ridges.
A fault along which strike-slip deformation is accompanied by a component of shortening transverse to the fault.
A fault along which strike-slip deformation is accompanied by a component of extension transverse to the fault.
A strike slip fault in which the faut plane is more or less vertical.
A mass of snow, ice or rocks moving rapidly down a steep mountain slope. Avalanches may be characterized as loose and turbulent, or slab; either type may be dry or wet according to the nature of the snow forming it, although dry snow usually forms loose avalanches and wet snow forms slabs. A large avalanche sweeps a current of air along with and in front of it as an avalanche wind, which supplements its already tremendous destructive force.
Compaction, part of the process of lithification involving mechanical dewatering of a sediment by progressive loading under several km of geomaterial [Wikipedia]
In geology and oceanography, diagenesis is any chemical, physical, or biological change undergone by a sediment after its initial deposition and during and after its lithification, exclusive of surface alteration (weathering) and metamorphism. These changes happen at relatively low temperatures and pressures and result in changes to the rock's original mineralogy and texture. The boundary between diagenesis and metamorphism, which occurs under conditions of higher temperature and pressure, is gradational. After deposition, sediments are compacted as they are buried beneath successive layers of sediment and cemented by minerals that precipitate from solution. Grains of sediment, rock fragments and fossils can be replaced by other minerals during diagenesis. Porosity usually decreases during diagenesis, except in rare cases such as dissolution of minerals and dolomitization.
Karst topography is a landscape shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone or dolomite. [Wikipedia]
A landslide (or landslip) is a geological phenomenon which includes a wide range of ground movement, such as rock falls, deep solidure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments. [Wikpedia]
The process of depositing material by water, wind, or glaciers.
Subsidence is the motion of a surface (usually, the Earth's surface) as it shifts downward relative to a datum such as sea-level. [Wikipedia]
Weathering is the decomposition of rocks, soils and their minerals through direct contact with the Earth's atmosphere. Weathering occurs in situ, or with no movement, and thus should not to be confused with erosion, which involves the movement and disintegration of rocks and minerals by agents such as water, ice, wind and gravity.
Earthquakes are caused by energy release during rapid slippage along a fault. [Wikipedia]
A type of seismic surface wave having a horizontal motion that is shear or transverse to the direction of propagation. Its velocity depends only on density and rigidity modulus, and not on bulk modulus. It is named after A. E. H. Love, the English mathematician who discovered it.
P waves are longitudinal or compressional waves, which means that the ground is alternately compressed and dilated in the direction of propagation. In solids these waves generally travel slightly less than twice as fast as S waves and can travel through any type of material. In air, these pressure waves take the form of sound waves, hence they travel at the speed of sound. Typical speeds are 330 m/s in air, 1450 m/s in water and about 5000 m/s in granite. P waves are sometimes called primary waves. When generated by an earthquake they are less destructive than the S waves and surface waves that follow them, due to their lesser amplitudes.
Body waves are seismic waves that travel through the lithosphere. Two kinds of body waves exist: P-waves and S-waves.
Surface waves are analogous to water waves and travel just under the Earth's surface. They travel more slowly than body waves. Because of their low frequency, long duration, and large amplitude, they can be the most destructive type of seismic wave. There are two types of surface waves: Rayleigh waves and Love waves. Theoretically, surface waves can be understood as systems of interacting P and/or S waves.
Seismic waves are phenomena that travel through the Earth or other elastic body, for example as the result of an earthquake, explosion, or some other process that imparts forces to the body. [Wikipedia]
S waves are transverse or shear waves, which means that the ground is displaced perpendicularly to the direction of propagation. In the case of horizontally polarized S waves, the ground moves alternately to one side and then the other. S waves can travel only through solids, as fluids (liquids and gases) do not support shear stresses. Their speed is about 60% of that of P waves in a given material. S waves are sometimes called secondary waves, and are several times larger in amplitude than P waves for earthquake sources.
Low amplitude, continuous earthquake activity often associated with magma movement.
Asymmetric heat flow in geology is an observation that the heat from upwelling mantle does not spread symmetrically away from the hot spot or rift due to differences in crust composition.
Continental drift is the movement of the Earth's continents relative to each other. [Wikipedia]
An extension event occurs when a seismic event causes an extension in the crust. [Wikipedia]
Post-glacial rebound (sometimes called continental rebound, isostatic rebound, isostatic adjustment or post-ice-age isostatic recovery) is the rise of land masses that were depressed by the huge weight of ice sheets during the last glacial period, through a process known as isostatic depression. [Wikipedia]
Plate convergence is the phenomena of two plates moving toward one another. [Wikipedia]
Plate divergence is the phenomena of plates drifting apart [Wikipedia]
A spreading event occurs whenever plates drift apart (Plate Divergence). [Wikipedia]
A tectonic ssemblage is a geological term for an accreted terrane of heterogeneous rocks. [Wikipedia]
The tectonic force is the force created by one tectonic plate pushing against another due to upwellings of the mantle, [Wikipedia]
The tectonic phenomena is the observable motions of the tectonic plates in the Earth's Lithosphere. [Wikipedia]
A terrane in geology is a fragment of crustal material formed on, or broken off from, one tectonic plate and accreted — ‘sutured’ — to crust lying on another plate. [Wikipedia]
The column of gases, ash, and larger rock fragments rising from a crater or other vent. If it is of sufficient volume and velocity, this gaseous column may reach many miles into the stratosphere, where high winds will carry it long distances.
An eruption from the side of a volcano (in contrast to a summit eruption.)
Tephra is air-fall material (of any size) produced by a volcanic eruption regardless of composition or fragment size. [Wikipedia]
Eruption Type 1 - produce juvenile clasts during explosive decompression from gas release. [Wikipedia]
A mantle plume is an upwelling of abnormally hot rock within the Earth's mantle. As the heads of mantle plumes can partly melt when they reach shallow depths, they are thought to be the cause of volcanic centers known as hotspots and probably also to have caused flood basalts. [Wikipedia]
In a Peléan eruption or nuée ardente (glowing cloud) eruptions a large amount of gas, dust, ash, and lava fragments are blown out of a central crater, fall back, and form avalanches that move downslope at speeds as great as 160 km per hour. These eruptions are usually associated with silicic magmas. A name for some pyroclastic flows is nuée ardente (French for ‘glowing cloud’); this was first used to describe the disastrous 1902 eruption of Mount Pelée on Martinique.[3] These pyroclastic flows glowed red in the dark. [Wikipedia]
Phreatic eruption is an explosion that follows the transformation of groundwater into steam. No incandescent or juvenile material is erupted.
Eruption Type 2 - Ejection of entrained particles during steam eruptions. [Wikipedia]
Plinian eruptions are characterized by paroxysmal ejection of large volume of ash and pumice as a well-defined eruption column or ‘jet;’ often precedes caldera collapse. The resulting tephra fallout covers an area of more than 500 square kilometers.
A series of hundreds of steam explosions preceding an eruption of the volcano A less intense geothermal event may result in a mud volcano. In 1949, Thomas Jaggar described this kind of activity as steam-blast eruptions. [Wikipedia]
Strombolian Eruptions are characterised by huge clots of molten lava bursting from the summit crater to form luminous arcs through the sky. Collecting on the flanks of the cone, lava clots combine to stream down the slopes in molten rivulets. The explosions are driven by bursts of gas slugs that rise faster than surrounding magma
A ring-shaped cloud of gas and suspended solid debris that moves radially outward at high velocity as a density flow from the base of a vertical eruption column accompanying a volcanic eruption or crater formation.
A geophysical phenomena involving the extrusion of rock that tends to form mountains or features like mountains over a period of time. [Wikipedia]
Moderate to violent ejection of solid or very viscous hot fragments of new lava in short-lived, cannon-like bursts. Ash and fine ash are emitted with gases and ascend to form a cauliflower-like eruption cloud.
An eruption column of hot volcanic ash and gas emitted into the atmosphere during an explosive volcanic eruption. [Wikipedia]
The sporadic radiant emission from the upper atmosphere over the middle and high latitudes.
The bow shock is a discontinuity that forms in the solar wind when the supersonic solar wind encounters the magnetic field of a planet, very similar to the shock wave that forms upstream of an aircraft moving at a supersonic speed.
A geomagnetic storm is a temporary disturbance of the Earths magnetosphere caused by a disturbance in space weather. Associated with solar coronal mass ejections (CME), coronal holes, or solar flares, a geomagnetic storm is caused by a solar wind shock wave which typically strikes the Earths magnetic field 24 to 36 hours after the event. This only happens if the shock wave travels in a direction toward Earth. The solar wind pressure on the magnetosphere will increase or decrease depending on the Sun's activity. These solar wind pressure changes modify the electric currents in the ionosphere.
The solar wind is a stream of charged particles (i.e., a plasma) which are ejected from the upper atmosphere of the sun. It consists mostly of high-energy electrons and protons (about 1 keV) that are able to escape the sun's gravity in part because of the high temperature of the corona and the high kinetic energy particles gain through a process that is not well understood at this time.
Space weather is the concept of changing environmental conditions in outer space. It is distinct from the concept of weather within a planetary atmosphere, and generally deals with the interactions of ambient radiation and matter within interplanetary, and occasionally interstellar space. Space weather describes the conditions in space that affect Earth and its technological systems. Our space weather is a consequence of the behavior of the sun, the nature of Earth's magnetic field, and our location in the solar system.
Flow of a fluid with its surface exposed to the atmosphere.
Percolation concerns the movement and filtering of fluids through porous materials.
The process or processes that cause the time required for a given radionuclide to move between two locations to be greater than the groundwater travel time, because of physical and chemical interactions between the radionuclide and the geohydrologic unit through which the radionuclide travels.
Runoff is a term used to describe the flow of water, from rain, snowmelt, or other sources, over the land surface, and is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source. If a nonpoint source contains man-made contaminants, the runoff is called nonpoint source pollution. A land area which produces runoff draining to a common point is called a watershed. When runoff flows along the ground, it can pick up soil contaminants such as petroleum, pesticides (in particular herbicides and insecticides), or fertilizers that become discharge or nonpoint source pollution.
Streamflow, or channel runoff, is the flow of water in streams, rivers, and other channels, and is a major element of the water cycle. It is one component of the runoff of water from the land to waterbodies, the other component being surface runoff. Water flowing in channels comes from surface runoff from adjacent hillslopes, from groundwater flow out of the ground, and from water discharged from pipes. The discharge of water flowing in a channel is measured using stream gauges or can be estimated by the Manning equation. The record of flow over time is called a hydrograph. Flooding occurs when the volume of water exceeds the capacity of the channel.
Aeration (also called aerification) is the process by which air is circulated through, mixed with or dissolved in a liquid or substance. [Wikipedia]
Bioturbation is the displacement and mixing of sediment particles by benthic fauna (animals) or flora (plants). The mediators of bioturbation are typically annelid worms (e.g. polychaetes, oligochaetes), bivalves (e.g. mussels, clams), gastropods, holothurians, or any other infaunal or epifaunal organisms. Faunal activities, such as burrowing, ingestion and defecation of sediment grains, construction and maintenance of galleries, and infilling of abandoned dwellings, displace sediment grains and mix the sediment matrix. In soil science, bioturbation is the physical rearrangement of the soil profile by soil life.
Cryoturbation (frost churning) refers to the mixing of materials from various horizons of the soil right down to the parent rock due to freezing and thawing. Cryoturbation occurs to varying degrees in most Gelisols (permafrost soils). The cause of crytoturbation lies in the way in which the repeated freezing of the soil during autumn causes the formation of ice wedges at the most easily erodible parts of the parent rock. If the parent rock is hard, this can cause quite deep erosion of the rock over many years. As this process continues, during the summer when an active layer forms in the soil this eroded material can easily move both from the soil surface downward and from the permafrost table upward. As this process occurs, the upper soil material gradually dries out (because the soil moisture moves from the warm surface layer to the colder layer at the phen of the permafrost) so that it forms a granular structure with many very distinctive crystalline shapes (such as ice lenses). Separation of coarse from fine soil materials produces distinctive patterned ground with different types of soil.
Diffusion or dispersion due to the effects of turbulent motions.
The periodic rising and falling of the earth's oceans and atmosphere. It results from the tide-producing forces of the moon and sun acting upon the rotating earth. This disturbance actually propagates as a wave through the atmosphere and along the surface of the waters of the earth. Atmospheric tides are always so designated, whereas the term “tide“ alone commonly implies the oceanic variety. Sometimes, the consequent horizontal movement of water along the coastlines is also called “tide,” but it is preferable to designate the latter as tidal current, reserving the name tide for the vertical wavelike movement.
Surface gravity waves on the ocean that are not growing or being sustained any longer by the wind.
Roll circulations approximately aligned with the surface stress vector that frequently occur in the upper boundary layer of oceans or lakes. Although similar in form to atmospheric longitudinal roll vortices, Langmuir circulations are thought to be driven by nonlinear interactions between the surface gravity wave field and the larger-scale turbulent motions within the mixed layer. They are sometimes called windrows because they form lines of surface debris or bubbles in their surface convergence zones. Their spatial scale is related to the depth of the mixed layer and their characteristic velocity is on the order of 8u*, where u* is the friction velocity in water. As a result of this scaling, Langmuir circulations generally require surface winds of at least 8 m s-1 in order to form. See coherent structures, longitudinal rolls.
(Also called littoral current.) The resultant current produced by waves being deflected at an angle by the shore. In this case the current runs roughly parallel to the shoreline. The longshore current is capable of carrying a certain amount of material as long as its velocity remains fairly constant; however, any obstruction, such as a submarine rock ridge or a land point cutting across the path of the current, will cause loss of velocity and consequent loss of carrying power.
In oceanography, densely packed, irregularly oval- shaped high and low pressure centers roughly 400 km (240 miles) in diameter in which current intensities are typically tenfold greater than the local means.
The global recirculation of water masses that determines today's climate.
Any process or series of processes by which parcels of ocean water with different properties are brought into intimate small-scale contact, so that molecular diffusion erases the differences between them.
Waves generated by seismic activity.
An ascending motion of subsurface water by which water from deeper layers is brought into the surface layer and is removed from the area of upwelling by divergent horizontal flow.
The climate of a natural region of small extent, for example, valley, forest, plantation, and park. Because of subtle differences in elevation and exposure, the climate may not be representative of the general climate of the region.
Climate for periods prior to the development of measuring instruments, including historic and geologic time, for which only proxy climate records are available.
all processes that remove material from an object, such as a glacier
A theoretical explanation of the process by which precipitation particles may form within a mixed cloud (composed of both ice crystals and liquid water drops).
The most common fracture type is conchoidal. This is a smoothly curved fracture that is familiar to people who have examined broken glass.
a fracture that produces a texture similar to broken children's clay. It is found in minerals that are generally massive and loosely consolidated.
Erosion is displacement of solids (soil, mud, rock and other particles) usually by the agents of currents such as, wind, water, or ice by downward or down-slope movement in response to gravity or by living organisms (in the case of bioerosion).
In geology, a fault or fault line is a planar rock fracture, which shows evidence of relative movement. Large faults within the Earth's crust are the result of shear motion and active fault zones are the causal locations of most earthquakes. Earthquakes are caused by energy release during rapid slippage along faults. The largest examples are at tectonic plate boundaries but many faults occur far from active plate boundaries. Since faults do not usually consist of a single, clean fracture, the term fault zone is used when referring to the zone of complex deformation that is associated with the fault plane.
The term fold is used in geology when one or a stack of originally flat and planar surfaces, such as sedimentary strata, are bent or curved as a result of plastic (i.e. permanent) deformation.
Jagged has sharp points or edges that catch on a finger that's rubbed across the surface.
Splintery is a fracture type that occurs in fibrous or finely acicular minerals and in minerals that have a relatively stronger structure in one direction than the other two.
Similar to conchoidal, just not as curved, but still smooth.
A coronal mass ejection (CME) is an ejection of material from the solar corona, usually observed with a white-light coronagraph. The ejected material is a plasma consisting primarily of electrons and protons (in addition to small quantities of heavier elements such as helium, oxygen, and iron), plus the entrained coronal magnetic field.
If a solar prominence occurs on the disc of the sun it appears darker than its background (due to the lower temperature of the plasma). These are referred to as solar filaments.
A flare is a violent explosion in the atmosphere of a star. Flares take place in the corona and chromosphere, heating plasma to tens of millions of kelvins and accelerating electrons, protons and heavier ions to near the speed of light. They produce electromagnetic radiation across the electromagnetic spectrum at all wavelengths from long-wave radio to the shortest wavelength gamma rays Most flares occur in active regions around sunspots, where intense magnetic fields emerge from the surface into the corona. Flares are powered by the sudden (timescales of minutes to tens of minutes) release of magnetic energy stored in the corona.
Granules on the photosphere are caused by convection currents (thermal columns, Bénard cells) of plasma within the Sconvective zone.
A solar prominence is a large bright feature extending outwards from the sun's surface, often in a loop configuration. Prominences are anchored to the solar surface in the photosphere, and extend outwards into the solar corona. While the corona consists of extremely hot ionized gases, known as plasma, which do not emit much visible light, prominences contain much cooler plasma, similar in composition to that of the chromosphere. A prominence forms over timescales of about a day, and stable prominences may persist in the corona for several months. Some prominences break apart and give rise to coronal mass ejections
process that multiple substances are in contact and have some consequence
Any departure introduced into an assumed steady state of a system. The magnitude is often assumed to be small so that product terms in the dependent variables may be neglected.
System is a set of interacting or interdependent entities, real or abstract, forming an integrated whole.
Oscillation, usually of a small amplitude, about a reference state.
System dynamics is an approach to understanding the behaviour of complex systems over time. It deals with internal feedback loops and time delays that affect the behaviour of the entire system. What makes using system dynamics different from other approaches to studying complex systems is the use of feedback loops and stocks and flows. These elements help describe how even seemingly simple systems display baffling nonlinearity
A wave disturbance with restoring forces that include buoyancy and the elastic compressibility of the fluid medium.
A wave disturbance in which buoyancy (or reduced gravity) acts as the restoring force on parcels displaced from hydrostatic equilibrium.
An unstable wave in a system of two homogeneous fluids with a velocity discontinuity at the interface.
1. Any wave motion in which no form of energy other than kinetic energy is present. In this general sense, Helmholtz waves, barotropic disturbances, Rossby waves, etc., are inertia waves. 2. More restrictedly, a wave motion in which the source of kinetic energy of the disturbance is the rotation of the fluid about some given axis. In the atmosphere a westerly wind system is such a source, the inertia waves here being, in general, stable. A similar analysis has been applied to smaller vortices, such as the hurricane. See inertial instability
A wave that propagates in density-stratified fluid under the influence of buoyancy forces.
A waveform disturbance that arises from Kelvin?Helmholtz instability.
A type of low-frequency gravity wave trapped to a vertical boundary, or the equator, which propagates anticlockwise (in the Northerm Hemisphere) around a basin.
Ocean surface waves that are nearly two-dimensional, in that the crests appear very long in comparison with the wavelength, and the energy propagation is concentrated in a narrow band around the mean wave direction.
Longitudinal waves are waves that have vibrations along or parallel to their direction of travel. They include waves in which the motion of the medium is in the same direction as the motion of the wave. Mechanical longitudinal waves have been also referred to as compressional waves or pressure waves
Rayleigh waves, also called ground roll, are surface waves that travel as ripples similar to those on the surface of water. The existence of these waves was predicted by John William Strutt, Lord Rayleigh, in 1885. They are slower than body waves, roughly 70% of the velocity of S waves, and have been asserted to be visible during an earthquake in an open space like a parking lot where the cars move up and down with the waves. Reports among seismologists suggest that the apparent motion may be due to distortion of the human eye during shaking. Anecdotally, placing people on shake tables causes the room to appear to ripple. In any case, waves of the reported amplitude, wavelength, and velocity of the visible waves have never been recorded instrumentally.
Rossby (or planetary) waves are large-scale motions in the ocean or atmosphere whose restoring force is the variation in Coriolis effect with latitude. The waves were first identified in the atmosphere in 1939 by Carl-Gustaf Arvid Rossby who went on to explain their motion. Rossby waves are a subset of inertial waves
A seiche is a standing wave in an enclosed or partially enclosed body of water. Seiches and seiche-related phenomena have been observed on lakes, reservoirs, bays and seas. The key requirement for formation of a seiche is that the body of water be at least partially bounded, allowing natural phenomena to form a standing wave.
An ocean wave with its length sufficiently large compared to the water depth (i.e., 25 or more times the depth)
With regard to atmospheric circulation, a progressive wave in the horizontal pattern of air motion with dimensions of cyclonic scale, as distinguished from a long wave.
A wave that is stationary with respect to the medium in which it is embedded, for example, two equal gravity waves moving in opposite directions.
Waves with a restoring force arising from variations in depth. The stretching or compression of displaced columns of water generates anomalous vorticity tending to drive them back to their original position.
A transverse wave is a wave that causes vibration in the medium in a perpendicular direction to its own motion. For example: if a wave moves along the x-axis, its disturbances are in the yz-plane. In other words, it causes medium disturbances across the two-dimensional plane that it is travelling in. Contrary to popular belief, transversal waves do not necessarily move up and down.
Any process that decreases the pH value of a subtance.
Adsorption is the accumulation of atoms or molecules on the surface of a material. This process creates a film of the adsorbate (the molecules or atoms being accumulated) on the adsorbent's surface. [Wikipedia]
Any process that increases the calcium concentration of a subtance.
A chemical process is a method or means of somehow changing one or more chemicals or chemical compounds. [Wikipedia]
Crystallization is the (natural or artificial) process of formation of solid crystals precipitating from a solution, melt or more rarely deposited directly from a gas. [Wikipedia]
Dissolution or solvation is the process of dissolving a solid substance into a solvent to yield a solution. [Wikipedia]
Electrolysis is a method of using an electric current to drive an otherwise non-spontaneous chemical reaction.
Fluorescence is a luminescence that is mostly found as an optical phenomenon in cold bodies, in which the molecular absorption of a photon triggers the emission of another photon with a longer wavelength. The energy difference between the absorbed and emitted photons ends up as molecular vibrations or heat. Usually the absorbed photon is in the ultraviolet range, and the emitted light is in the visible range, but this depends on the absorbance curve and Stokes shift of the particular fluorophore. Fluorescence is named after the mineral fluorite, composed of calcium fluoride, which often exhibits this phenomenon.
Hydrolysis is a chemical reaction during which molecules of water (H2O) are split into hydrogen (H) and hydroxide anions (OH−) in the process of a chemical mechanism.
In general, leaching is the extraction of certain materials from a carrier into a liquid (usually, but not always a solvent).
In chemistry, neutralization is a chemical reaction (also called a water forming reaction since a water molecule is formed during the process) in which an acid and a base or alkali (soluble base) react to produce salt and water (H2O). During the process, hydrogen ions H+ (a bare proton) from the acid (proton donor) or a hydronium ion H3O+ and hydroxide ions OH_ or oxide ions O2_ from the base (proton acceptor) react together to form a water molecule H2O. [Wikipedia]
Nucleation is the extremely localized budding of a distinct thermodynamic phase. Some examples of phases that may form via nucleation in liquids are gaseous bubbles, crystals, or glassy regions.
Reaction of a substance with oxygen or incorporation of oxygen into a molecule.
Continues to glow after light source is removed
Photodissociation, photolysis, or photodecomposition is a chemical reaction in which a chemical compound is broken down by photons. It is defined as the interaction of one or more photons with one target molecule. [Wikipedia]
Glows when heated
Titration is a common laboratory method of quantitative chemical analysis that is used to determine the unknown concentration of a known reactant.
Glows when struck
Transport of energy (charge) solely as a consequence of random motions of individual molecules (ions, electrons) not moving together in coherent groups.
In hydrodynamics, the motion of a fluid particle induced by the passage of a progressive gravity wave.
The transport of mass motion momentum solely by the random motions of individual molecules not moving together in coherent groups.
The phase transition of a substance passing from the liquid to the solid state; solidification; the opposite of fusion.
Ionization is the physical process of converting an atom or molecule into an ion by changing the difference between the number of protons and electrons. This process works slightly differently depending on whether an ion with a positive or a negative electric charge is being produced. A positive electric charge is produced when an electron bond to an atom or molecule absorbs enough energy from an external source to escape from the electric potential barrier that originally confined it, where the amount of energy required is called the Ionization potential. A negative electric charge is produced when a free electron collides with an atom and is subsequently caught inside the electric potential barrier, releasing any excess energy.
change of state by state variable change
The physical process by which a liquid is transformed to the gaseous state; the opposite of condensation.
The process in which incident radiant energy is retained by a substance.
Scattering of sound or ultrasound in the direction of the source.
scattering of waves (photons) that reverse the direction of propagation
In radar, a general term for the appearance, on a radar display, of the radio signal scattered or reflected from a target. The characteristics of a radar echo are determined by 1) the waveform, frequency, and power of the incident wave; 2) the range and velocity of the target with respect to the radar; and 3) the size, shape, and composition of the target.
Line-of-sight propagation refers to electromagnetic radiation or electromagnetic waves travelling in a straight line. The rays or waves are deviated or reflected by obstructions and cannot travel over the horizon or behind obstacles. Beyond that, material disperses the rays respectively the energy of the waves.
Wave propagation is any of the ways in which waves travel through a medium (waveguide). With respect to the direction of the oscillation relative to the propagation direction, we can distinguish between longitudinal wave and transverse waves. Another useful parameter for describing the propagation is the wave velocity that mostly depends on some kind of density of the medium. For electromagnetic waves, propagation may occur in a vacuum as well as in a material medium.
A change of direction and possibly amplitude of an electromagnetic, acoustic, or any other wave propagating in a material medium, homogeneous on the scale of the wavelength, as a consequence of spatial variation in the properties of the medium.
In a broad sense, the process by which matter is excited to radiate by an external source of electromagnetic radiation, as distinguished from emission of radiation by matter, which occurs even in the absence of such a source.
A community is a social group of organisms sharing an environment, normally with shared interests.
pH is a measure of the acidity or basicity of a solution. It is defined as the cologarithm of the activity of dissolved hydrogen ions (H+). Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations. The pH scale is not an absolute scale; it is relative to a set of standard solutions whose pH is established by international agreement. [Wikipedia]
The total amount of solute species that will remain indefinitely in a solution maintained at constant temperature and pressure in contact with the solid crystals from which the solutes were derived.
Often the greatest magnitude at a given point of any spatially and temporally varying physical quantity governed by a wave equation; can also mean the spatial part of a time-harmonic wave function.
The amount by which the water vapor in the air must be increased to achieve saturation without changing the environmental temperature and pressure.
The rate at which adjacent flow is converging along an axis oriented normal to the flow at the point in question.
The rate at which adjacent flow diverges along an axis oriented normal to the flow at the point in question; the opposite of confluence.
The exchange coefficient for the diffusion of a conservative property by eddies in a turbulent flow.
An approximation to the gradient Richardson number formed by approximating local gradients by finite difference across layers.
In Raman spectroscopy, the depolarization ratio is the intensity ratio between the perpendicular component and the parallel component of the Raman scattered light.
A relationship between the advective and diffusive components of solute transport expressed as the ratio of the product of the average interstitial velocity, times the characteristic length, divided by the coefficient of molecular diffusion; small values indicate diffusion dominance, large values indicate advection dominance.
The ratio of the effective permeability for a given flow phase to the intrinsic permeability of the porous medium (WMO, 1974). The ratio of the effective and specific permeabilities.
The ratio of the average linear velocity of groundwater to the velocity of the retarded constituent at C/Co=0.5.
The dimensionless ratio of the inertial force (∼U2/L) to the viscous force (∼ νU/L2) in the Navier–Stokes equations, where U is a characteristic velocity, L is a characteristic length, and ν is the kinematic viscosity of the fluid; thus, Re=ULv. The Reynolds number is of great importance in the theory of hydrodynamic stability and the origin of turbulence. The inertia force generates vortex stretching and nonlinear interactions and hence creates randomness. Turbulence occurs when the inertia term dominates the viscous term, that is, when the Reynolds number is large. For many engineering flows, turbulence occurs when Re > Rec, where the critical Reynolds number is roughly Rec = 2100.
A dimensionless number relating the ratio of inertial to Coriolis forces for a given flow of a rotating fluid.
The ratio of the Volume of water which the porous medium, after being saturated, will retain against the pull of gravity to the volume of the porous medium.
The volume of water released from or taken into storage per unit volume of the porous medium per unit change in head.
The ratio of the volume of water which the porous medium after being saturated, will yield by gravity to the volume of the porous medium.
The ratio of a region's total precipitation to its external precipitation originating as evaporation from the oceans as opposed to evapotranspiration from the land.
That portion of the total potential energy that may be converted to kinetic energy in an adiabatically enclosed system.
The energy needed to lift an air parcel vertically and pseudoadiabatically from its originating level to its level of free convection (LFC).
Energy per unit area.
Analogous to convective available potential energy, except that it is related to the negative buoyancy associated with evaporative cooling of liquid water within a sinking cloudy air parcel.
The energy required to extract water from a porous medium to overcome the capillary and adsorptive forces.
Infrequently, any energy propagated by a physical quantity governed by a wave equation.
The sum of the energy-related components of a soil-water system; i.e., the sum of the gravitational, matric, and osmotic components.
A form of energy arising from the motion of a system against a force, existing only in the process of energy conversion.
Solar radiation absorbed by the atmosphere's constituent gases, suspended material, clouds, or by the earth's surface.
>Heat flux averaged over a layer of air, such as the boundary layer; heat-flux divergence or difference between the top and bottom of a layer.
The extinction coefficient for a particular substance is a measure of how well it scatters and absorbs electromagnetic radiation (EM waves). If the EM wave can pass through very easily, the material has a low extinction coefficient. Conversely, if the radiation hardly penetrates the material, but rather quickly becomes extinct within it, the extinction coefficient is high.
A radiometric term for the rate at which radiant energy in a set of directions confined to a unit solid angle around a particular direction is transferred across unit area of a surface (real or imaginary) projected onto this direction.
Radiant energy per unit time passing some specified area from one side.
In radiation, the net flux of radiation into or out of a system. As a consequence of radiative forcing there must be some change to the nonradiative energy states of the system.
The total electromagnetic radiation emitted by the sun.
The radiance per unit wavelength or wavenumber interval.
Longwave radiation originating by thermal emission from a planetary surface and/or its atmosphere
The ratio of reflected flux density to incident flux density, referenced to some surface.
1. Generally, some measure of the water vapor content of air. The multiplicity of humidity measures is partly due to different methods of measurement and partly because the conservative measures (mixing ratio, specific humidity) cover an extremely wide dynamic range, as a result of the rapid variation of saturation vapor pressure with temperature. 2. Popularly, same as relative humidity.
A general term referring to the radiation reflected from, or scattered back through, a given surface in response to radiation incident on the surface with the same wavelength or wavelength range.
A thermodynamic function of state; the value of the mixing ratio of saturated air at the given temperature and pressure.
In a system of moist air, the (dimensionless) ratio of the mass of water vapor to the total mass of the system.
A measure of the mean thermodynamic stability in a layer beneath 700 mb.
The Common Sense Climate Index is a simple measure of the degree (if any) to which practical climate change is occurring. The index is a composite of several everyday climate indicators. It is expected to have positive values when warming occurs and negative values for cooling. If the Index reaches and consistently maintains a value of 1 or more, the climate change should be noticeable to most people who have lived at that location for a few decades.
The full range of hydrologic parameters, which include the depth of water, duration of inundation, and the timing and distribution of freshwater flow.
The representation in a numerical model of the turbulent transports of heat and moisture by nonprecipitating cumulus clouds with cloud tops below 3000 m above the surface.
The volume of water an aquifer releases from or takes into storage per unit surface area of the aquifer per unit change in head (virtually equal to the specific yield in an unconfined aquifer).
The effect of (primarily) aerosols, through their total optical depth, in reducing the transmission of direct solar radiation to the surface below that through a purely molecular atmosphere. Turbidity is the cloudiness or haziness of a fluid, or of air, caused by individual particles (suspended solids) that are generally invisible to the naked eye, similar to smoke in air.
A measure of strength of the middle-latitude westerlies, usually expressed as the horizontal pressure difference between 35 and 55N latitude, or as the corresponding geostrophic wind.
1. The ratio of the mass of any substance to the volume occupied by it (usually expressed in kilograms per cubic meter, but any other unit system may be used); the reciprocal of specific volume.
The vertical integral of the density of absorbers between two altitudes; used mainly in determining the transmission through an absorbing gas.
The density of a unit of water after it is raised by an adiabatic process to the surface, i.e., determined from in-situ salinity and potential temperature (AGI, 1980). Density that would be reached by a compressible fluid if it were adiabatically compressed or expanded to a standard pressure.
The observed permeability of a porous medium to one fluid phase under conditions of physical interaction between this phase and other fluid phases present.
A measure of the relative ease with which a porous medium can transmit a fluid under a potential gradient and is a property of the medium alone (after Lohman and others, 1972). The property of a porous medium itself that expresses the ease with which gases, liquids, or other substances can pass through it.
The rate of flow of water through a unit cross-sectional area under a unit hydraulic gradient at the prevailing temperature (field permeability coefficient) or adjusted to a temperature of 150C (60-F).
The rate of discharge of water from the well divided by the drawdown of the water level within the well.
The rate of discharge of groundwater per unit area of a porous medium measured at right angle to the direction of flow.
The permeability measured when the rock contains only one fluid.
The electromagnetic (EM) spectrum is the range of all possible electromagnetic radiation. The electromagnetic spectrum (usually just spectrum) of an object is the characteristic distribution of electromagnetic radiation from that object.
Color of the powder of a substance.
The pressure exerted by the atmosphere as a consequence of gravitational attraction exerted upon the column of air lying directly above the point in question.
The character and amount of atmospheric pressure change during a specified period of time, often a three-hour period preceding an observation.
The pressure that a component of a gaseous mixture would have if it alone occupied the same volume at the same temperature as the mixture.
Force per unit area.
The derivative of pressure
The atmospheric pressure at mean sea level, either directly measured or, most commonly, empirically determined from the observed station pressure.
In general, an equation expressing a balance of quantities in the sense that the local or individual rates of change are zero.
The rate of flow of some quantity, often used in reference to the flow of some form of energy.
In physics, the angular momentum of an object rotating about some reference point is the measure of the extent to which the object will continue to rotate about that point unless acted upon by an external torque. In particular, if a point mass rotates about an axis, then the angular momentum with respect to a point on the axis is related to the mass of the object, the velocity and the distance of the mass to the axis. While the motion associated with linear momentum has no absolute frame of reference, the rotation associated with angular momentum is sometimes spoken of as being measured relative to the fixed stars.
The vertically averaged vorticity of a layer divided by layer thickness.
The vorticity as measured in a system of coordinates fixed on the earth's surface. Usually, only the vertical component of the vorticity is meant.
Description of the form of an object
A measure of the extinction due to scattering of monochromatic radiation as it traverses a medium containing scattering particles.
The greatest distance in a given direction at which it is just possible to see and identify with the unaided eye
A measure (or condition) of height, especially of great height, as a mountain top or aircraft flight level.
The vertical distance above mean sea level of the ground at the meteorological station.
After U.S.weather observing practice, the ceiling classification applied to a ceiling height that is determined in any of the following ways: 1) by means of a convective-cloud height diagram or dewpoint formula; 2) from the known heights of unobscured portions of natural landmarks, or objects more than one and one-half nautical miles from any runway of the airport; 3) on the basis of observational experience, provided the sky is not obscured by surface-based hydrometeors or lithometeors, and other guides are lacking or considered unreliable; or 4) determined by ceilometer or ceiling light when the penetration of the light beam is in excess of normal for the particular height and type of layer, or when the elevation angle of the clinometer or ceilometer-detector scanner exceeds 84?.
In aviation, a Flight Level (FL) is a standard nominal altitude of an aircraft, referenced to a world-wide fixed pressure datum of 1013.25 hPa or the equivalent setting, 29.921 inHg (the average sea-level pressure). It is not necessarily the same as the aircraft's true altitude above mean sea level.
The Secchi disk is a device used to measure water transparency in open waters of lakes, bays, and the ocean. A pattern is drawn or painted onto a card or acrylic, mounted on a pole or line, and lowered slowly in the water. The depth at which the pattern on the disk is no longer visible is taken as a measure of the transparency of the water. This measure is known as the Secchi depth and is related to water turbidity.
In topography, prominence, also known as autonomous height, relative height or shoulder drop (in America) or prime factor (in Europe), is a concept used in the categorization of hills and mountains, also known as peaks. It is a measure of the independent stature of a summit.
Radar cross section (RCS) describes the extent to which an object reflects an incident electromagnetic wave. It is a measure of the strength of the radar signal backscattered from a target object for a given incident wave power..
The optical thickness measured vertically above some given altitude. Optical depth is dimensionless and may be used to specify many different radiative characteristics of the atmosphere.
The total atmospheric water vapor contained in a vertical column of unit cross-sectional area extending between any two specified levels.
The depth of snow that has fallen.
The rate of change with time of the velocity vector of a particle.
Airspeed is the speed of an aircraft relative to the air. There are several different measures of airspeed: indicated airspeed, calibrated airspeed, equivalent airspeed and true airspeed.
Ground speed is the speed of an aircraft relative to the ground. It is the sum of the aircraft's true airspeed and the current wind and weather conditions; a headwind subtracts from the ground speed, while a tailwind adds to it. Winds at other angles to the heading will have components of either headwind or tailwind as well as a crosswind component.
The component of a three-dimensional velocity vector oriented along the radial direction from the origin point or axis in polar, cylindrical, or spherical coordinates. In connection with Doppler radar, the radial velocity component is called Doppler velocity.
The component of the acceleration directed along the velocity vector (streamline), with magnitude equal to the rate of change of speed of the parcel dV/dt, where V is the speed.
The time rate of change of a position vector; that is, a change of position expressed in terms of speed and direction.
Antenna temperature is a way of expressing the brightness of a radiation source - it is proportional to the power per unit area emitted by the source. In most cases where it is used it corresponds to the thermodynamic or physical temperature of the source being observed. It thus relates the power emitted by the source to an interesting physical property of that source.
A descriptive measure of radiation in terms of the temperature of a hypothetical blackbody emitting an identical amount of radiation at the same wavelength.
The temperature to which a given air parcel must be cooled at constant pressure and constant water vapor content in order for saturation to occur.
The temperature at which motionless saturated air would induce, in a sedentary worker wearing ordinary indoor clothing, the same sensation of comfort as that induced by the actual conditions of temperature, humidity, and air movement. Effective temperature is used as a guide in air-conditioning practice, and, on the comfort chart (American Society of Heating and Air Conditioning Engineers), it appears as a family of curves that serves as one coordinate in defining comfort zones.
The temperature that a parcel would have if brought adiabatically and reversibly from its initial state to a standard reference pressure, typically 100 kPa.
The temperature an air parcel would have if cooled from its initial state adiabatically to saturation, and thence brought to 1000 mb by a moist-adiabatic process.
A means of quantifying the threat of rapid cooling during breezy or windy conditions that may result in hypothermia in cold conditions.
The environmental lapse rate of temperature in an atmosphere in which the density is constant with height (homogeneous atmosphere), equal to g/R, where g is the acceleration of gravity and R the gas constant.
A process lapse rate of temperature, the rate of decrease of temperature with height of a parcel of dry air lifted by a reversible adiabatic process through an atmosphere in hydrostatic equilibrium.
The rate of decrease of temperature with elevation
The derivative of temperature with respect to depth.
The derivative of temperature.
The derivative of temperature with respect to height.
The geologic time scale is a chronologic schema (or idealized model) relating stratigraphy to time that is used by geologists, paleontologists and other earth scientists to describe the timing and relationships between events that have occurred during the history of the Earth. [Wikipedia]
The interval of time between volcanic eruptions.
This is a reference to time as a dependent variable
The frequency at which a displaced parcel will oscillate when displaced vertically within a statically stable environment.
The expansion or spreading out of a vector field; also, a precise measure thereof.
The rate of recurrence of any periodic phenomenon, often associated with waves of all kinds. Without qualification frequency often means temporal frequency, the rate of recurrence of a time-varying function, but could mean spatial frequency, the rate of recurrence of a space-varying function. Spatial frequency is the reciprocal of the repeat distance (sometimes the wavelength). The dimensions of (temporal) frequency are inverse time. A common unit for frequency is cycle per second, formerly abbreviated cps, but superseded by hertz, abbreviated as Hz.
The spreading rate is a measure of how fast plate divergence is occurring. [Wikipedia]
An atmosphere is a layer of gases that may surround a material body of sufficient mass,[1] by the gravity of the body, and are retained for a longer duration if gravity is high and the atmosphere's temperature is low. [Wikipedia]
The cryosphere collectively describes the portions of a planetary surface in frozen form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps and ice sheets, and frozen ground (which includes permafrost). [Wikipedia]
The term Geosphere is often used to refer to the densest (solid) parts of a planet, which consist mostly of rock and regolith [Wikipedia]
A hydrosphere in physical geography describes the combined mass of water found on, under, and over the surface of a planet. [Wikipedia]
The part of a planetary surface that is a solid
An ocean is a major body of saline water, and a principal component of the hydrosphere. [Wikipedia]
The surface of the planet defined by solid and/or liquid layers
A qusai-horizontal surface spanning all or part of a planet that corresponds to a constant value of some parameter
A body or substance which does not originate from Earth. [Wikipedia]
A maximum in large-particle concentrations observed in the lower stratosphere between 15 and 25 km.
The top of the mesosphere and the base of the thermosphere. The mesopause is usually located at heights of 85?95 km, and is the site of the coldest temperatures in the atmosphere. Temperatures as low as 100 K (- 173?C) have been measured at the mesopause by rockets. See atmospheric shell.
The bottom layer of the troposphere that is in contact with the surface of the earth.
A region of negative buoyancy below an existing level of free convection (LFC) where energy must be supplied to the parcel to maintain its ascent.
A layer of air tens of meters thick at the bottom of the atmosphere where the variation of vertical turbulent flux with altitude is less than 10% of its magnitude.
A layer within the atmosphere bounded below by the surface, and above by a more or less sharp discontinuity in some atmospheric property. Internal boundary layers are associated with the horizontal advection of air across a discontinuity in some property of the surface (e.g., aerodynamic roughness length or surface heat flux) and can be viewed as layers in which the atmosphere is adjusting to new surface properties. See thermal internal boundary layer, mechanical internal boundary layer.
(Abbreviated MIBL.) An internal boundary layer caused by advection of air across a discontinuity in surface roughness. When the new surface is rougher than the old one, the MIBL depth grows roughly as the 0.8 power of the ratio of the two roughness lengths. In this example, the MIBL grows to include the whole surface layer.
A type of atmospheric boundary layer characterized by vigorous turbulence tending to stir and uniformly mix, primarily in the vertical, quantities such as conservative tracer concentrations, potential temperature, and momentum or wind speed.
The cool layer of air adjacent to the ground that forms at night. At night under clear skies, radiation to space cools the land surface, which in turn cools the adjacent air through processes of molecular conduction, turbulence, and radiative transfer. This causes a stable boundary layer to form and grow to depths of a few hundreds of meters, depending on the season. Many interacting processes can occur within the statically stable nocturnal boundary layer: patchy sporadic turbulence, internal gravity waves, drainage flows, inertial oscillations, and nocturnal jets.
For flow over a hill, the top layer in the boundary layer that accelerates relative to its upstream value due to the Bernoulli effect.
The bottom layer of the troposphere that is in contact with the surface of the earth. It is often turbulent and is capped by a statically stable layer of air or temperature inversion.
The middle portion of the nocturnal atmospheric boundary layer characterized by weak sporadic turbulence and initially uniformly mixed potential temperature and pollutants remaining from the mixed layer of the previous day.
Same as transition layer. The lowest atmospheric layer immediately adjacent to a surface covered with relatively large roughness elements such as stones, vegetation, trees, or buildings.
Level at which water vapor to condense
On a thermodynamic diagram, the point of intersection of a sounding curve (representing the vertical distribution of temperature in an atmospheric column) with the saturation mixing ratio line corresponding to the average mixing ratio in the surface layer.
Level of free convection
The altitude interval throughout which ice-phase precipitation melts as it descends. The top of the melting layer is the melting level. The melting layer may be several hundred meters deep, reflecting the time it takes for all the hydrometeors to undergo the transition from solid to liquid phase. The temperature of the melting layer is typically 0?C or slightly warmer. See bright band.
The altitude at which ice crystals and snowflakes begin to melt as they descend through the atmosphere. In cloud physics and in radar meteorology, this is the accepted term for the 0?C constant-temperature surface (see bright band). It is physically more apt than the corresponding operational term, freezing level, for melting of pure ice must begin very near 0?C, but freezing of liquid water can occur over a broad range of temperatures (between 0? and -40?C; see supercooling). See also freezing point, ice point, melting point.
A layer in the middle or upper troposphere in widespread precipitation in which ice crystals form in small convective cells and fall to lower altitudes.
The elevation band on a mountain or orographic barrier that receives the greatest precipitation for a seasonal or annual average.
An aquatic ecosystem is an ecosystem located in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems.
The term coral reef generally refers to a marine ecosystem in which the main organisms are corals that house algal symbionts within their tissues. These ecosystems require: 1) fully marine waters; 2) warm temperatures; and 3) ample sunlight. They are therefore restricted to shallow waters of tropical and subtropical regions. Corals that do not have algal symbionts can also form significant reef communities in deeper, darker, and colder waters, but these communities are distinguished as cold-water coral bioherms. The more technical definition of coral reef includes an additional geological requirement that the reef organisms produce enough calcium carbonate to build the physical reef structure. The coral reef community lives only on the surface veneer of the reef, on top of already existing skeletal material left behind by previous reef-builders. Many processes act to break down the skeletal material and reef as soon it is laid down by organisms. These include mechanical processes such as waves and currents, and a wide array of biological processes (e.g., bioerosion). Some of the best known bioeroders are large organisms such as parrotfish and sponges, but much of the bioerosion occurs at the microscopic scale by organisms such as algae and fungi. A coral reef is produced only if the coral reef community produces more calcium carbonate than is removed. Indeed, some coral reef communities grow too slowly to build a reef.
An irregular zone of extremely tall trees, rising above the mean canopy
A forest is an area with a high density of trees. There are many definitions of a forest, based on various criteria. These plant communities cover large areas of the globe and function as habitats for organisms, hydrologic flow modulators, and soil conservers, constituting one of the most important aspects of the Earth's biosphere.
Grasslands are areas where the vegetation is dominated by grasses (Poaceae) and other herbaceous (non-woody) plants (forbs). Plants of the sedge (Cyperacae) and rush (Juncaceae) families can also be frequent in grasslands. Grasslands occur naturally on all continents except Antarctica, and in many other areas they have replaced the natural vegetation due to human influence. In temperate latitudes, such as north-west Europe, grasslands are dominated by perennial species, whereas in warmer climates annual species form a greater component of the vegetation.
Montane is a biogeographic term which refers to highland areas located below the subalpine zone.[1] Montane regions generally have cooler temperatures and often have higher rainfall than the adjacent lowland regions, and are frequently home to distinct communities of plants and animals. [Wikipedia]
A savanna or savannah is a tropical or subtropical woodland ecosystem. Savannas are characterised by the trees being sufficiently small or widely spaced so that the canopy does not close. It is often believed that savannas are characterized by widely spaced, scattered trees, however in many savanna communities tree densities are higher and trees are more regularly spaced than in forest communities. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses. Savannas are also characterised by seasonal water availability, with the majority of rainfall being confined to one season of the year. Savannas can be associated with several types of biomes. Savannas are frequently seen as a transitional zone, occurring between forest regions and desert regions.
Scrubland is plant community characterized by scrub vegetation. Scrub consists of low shrubs, mixed with grasses, herbs, and geophytes. Scrublands are sometimes known as heathlands. Scrublands may be either naturally occurring or the result of human activity. They may be the mature vegetation type in a particular region and remain stable over time, or a transitional community that occurs temporarily as the result of a disturbance, such as a major fire. Many people do not live in scrubland because of the fires that can easily occur.
biome characterized by coniferous forests
The A climate classification, also known as the Tropical climate classification, is characterized as being consistently warm with all months averaging above 18 degrees C and having annual precipitation exceeds potential evapotranspiration (POTET).
The Af climate classification, also known as the tropical rain forest climate classification, is characterized by monthly precipitation in excess of 6 cm all months out of year.
The Am climate classification, also known as Tropical Monsoon Climate, is characterized by a short marked dry season with 1 or more months receiving less than 6 cm of precipitation, an otherwise excessively wet rainy season, and ITCZ dominance for 6 - 12 months out of the year.
The Aw climate classification, also known as Tropical Savanna climate classification, is characterized by a summer wet season, winter dry season, and ITCZ dominance for 6 months or less.
Potential evapotranspiration (POTET) exceeds precipitation in all B climates. Subdivisions are based on precipitation timing and amount and mean annual temperature.
The BS climate classification, also known as semiarid climate classification, is characterized by having precipitation amounts greater than 1/2 potential evapotranspiration (POTET), but not equal to it.
The BSh climate classification, also known as the hot low-latitude steppe, is characterized by having mean annual temperatures greater than 18 degree C.
The BSk climate classification, also known as cold midlatitude steppe climate classification, is characterized by having mean annual temperatures less than 18 degree C.
The BW climate classification, also known as the arid climate classification, is characterized by having precipitation amounts less than 1/2 potential evapotranspiration (POTET).
the BWh climate classification, also known as the hot low-latitude desert, is characterized by having mean annual temperatures greater than 18 degree C.
The BWk climate classification, also known as the cold midlatitude desert, is characterized by having mean annual temperatures less than 18 degree C.
The Cfa climate classification is characterized by year-round precipitation, hot summers, and having the warmest month above 22 degree C.
The Cfb climate classfication receives year-round precipitation, its warmest month is below 22 degree C and has 4 months above 10 degree C.
The Cfc climate classification is charactericized by year-round precipitation and having 1 - 3 months with temperatures above 10 degree C.
The Csa climate classification is characterized by pronounced summer droughts with 70% of precipitation in the winter and hot summers with its warmest month above 22 degree C.
the Cwa climate classification is characterized by winter drought, summer's wettest month getting 10 times more precipitation than driest winter month, and the warmest month being above 22 degree C.
The D climate classification, also known as the microthermal climate classification, is characterized by by having the warmest month of the year above 10 degree C and the coldest below 0 degree C.
The Dfa climate classification is characterized by having year-round precipitation and warmest month temperatures above 22 degree C.
The Dfb climate classifcation is characterized by having year-round precipitation and warmest month temperatures below 22 degree C.
The Dfc climate classification is characterized by having year-round precipitation and having 1 - 4 months above 10 degree C.
A nautical term for the equatorial trough, with special reference to the light and variable nature of the winds.
The Dwa climate classification is characterized by winter drought and warmest month temperatures above 22 degree C.
The Dwb climate classification is characterized by winter drought and warmest month temperatures below 22 degree C.
The Dwc climate classification is characterized by winter drought and haviong 1 - 4 months with temperatures above 10 degrees C.
The Dwd climate classification is characterized by winter drought and having coldest month temperatures below -38 degree C (in Siberia only).
The EF climate classification, also known as the Ice Cap climate classification, is characterized by having warmest month temperatures below 0 degrees C and having precipitation exceeding very small potential evapotranspiration (POTET).
The EM climate classification, also known as the polar marine climate classification, is characterized by all months having temperatures above -7 degree C, warmest month above 0 degree C, and annual temperatures less than 17 degree C.
The ET climate classification, also known as the tundra climate classification, is characterizex by warmest month temperatures between 0 - 10 degree C, precipitation exceeds small potential evapotranspiration demand, and has snow cover 8 - 10 months out of the year.
(Also called maritime climate, oceanic climate.) A regional climate under the predominant influence of the sea, characterized by relatively small seasonal variations and high atmospheric moisture content; the antithesis of a continental climate.
A region of sharply reduced precipitation on the lee side of an orographic barrier, as compared with regions upwind of the barrier.
Alpine tundra is an ecozone that does not contain trees because it has high altitude. Alpine tundra occurs at high enough altitude at any latitude on Earth. Alpine tundra also lacks trees, but the lower part does not have permafrost, and alpine soils are generally better drained than permafrost soils. Alpine tundra transitions to subalpine forests below the tree line; stunted forests occurring at the forest-tundra ecotone are known as Krummholz. Alpine tundra occurs in an alpine zone
Soil within which the moisture has predominantly changed to ice, the unfrozen portion being in vapor phase. Ice within the soil bonds (adfreezes) adjacent soil particles and renders frozen ground very hard. Permanently frozen ground is called permafrost. Dry frozen ground is relatively loose and crumbly because of the lack of bonding ice. Frozen ground is sometimes inadvisedly called frost or ground frost.
An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 square km (19,305 square mile).
Specifically, ice formed by the freezing of seawater; as opposed, principally, to land ice. Generally, any ice floating in the sea.
In physical geography, tundra is an area where the tree growth is hindered by low temperatures and short growing seasons. There are two types of tundra: Arctic tundra (which also occurs in Antarctica), and alpine tundra. In tundra, the vegetation is composed of dwarf shrubs, sedges and grasses, mosses, and lichens. Scattered trees grow in some tundra. The ecotone (or ecological boundary region) between the tundra and the forest is known as the tree line or timberline.
The asthenosphere is a portion of the upper mantle just below the lithosphere. Seismic waves pass relatively slowly through the asthenosphere, compared to the overlying lithospheric mantle, thus it has been called the low-velocity zone. [Wikipedia]
A batholith is a large emplacement of igneous intrusive (also called plutonic) rock that forms from cooled magma deep in the Earth's crust. Batholiths are almost always made mostly of felsic or intermediate rock-types, such as granite, quartz monzonite, or diorite (see also granite dome).There is also an important geographic usage of the term batholith. For a geographer, a batholith is an exposed area of mostly continuous plutonic rock that covers an area larger than 100 square kilometers. [Wikipedia]
D layer is the layer which separates the mantle from the core. D may consist of material from subducted slabs that descended and came to rest at the core-mantle boundary and/or from a new mineral polymorph discovered in perovskite called post-perovskite.[Wikipedia]
The central most structure inside the earth. The core does not allow shear waves to pass through it, while the speed of travel (seismic velocity) is different in the other layers. [Wikipedia]
The crust is the outermost solid shell of a rocky planet or moon, which is chemically distinct from the underlying mantle. [Wikipedia]
Dikes, long, planar (sheet) igneous intrusions, enter along cracks, and therefore often form in large numbers in areas that are being actively deformed. [Wikipedia]
or Surface Feature is a distinct recognizable structure within a larger context such as a stream bed, fissure, dike, etc.
A geologic or geomorphic province is a spatial entity with common geologic/geomorphic attributes. A province may include a single dominant structural element such as a basin or a fold belt, or a number of contiguous related elements. Most commonly, provinces are classified by age, origin, or mineral resource. [Wikipedia]
A dike swarm or dyke swarm in geology is a major group of parallel, linear, or radially oriented dikes intruded within continental crust. [Wikipedia]
The core-mantle boundary. This discontinuity is due to the differences between the acoustic impedances of the solid mantle and the molten outer core. P-wave velocities are much slower in the outer core than in the deep mantle while S-waves do not exist at all in the liquid portion of the core. Corresponds to top of D``. [Wikipedia]
The solid inner core was discovered in 1936 by Inge Lehmann and is generally believed to be composed primarily of iron and some nickel.[Wikipedia]
#Aseismic
Boundary between Asthenosphere and Lithosphere. It is the discontinuity in seismic velocity near a depth of 220 km. It appears beneath continents, but not usually beneath oceans, and does not readily appear in globally-averaged studies [Wikipedia]
In the Earth, the lithosphere includes the crust and the uppermost mantle, which constitute the hard and rigid outer layer of the planet. The division of Earth's outer layers into lithosphere and asthenosphere should not be confused with the chemical subdivision of the outer Earth into mantle, and crust. All crust is in the lithosphere, but lithosphere generally contains more mantle than crust. [Wikipedia]
[Pluton] Igneous intrusion - A lopolith is a large igneous intrusion which is lenticular in shape with a depressed central region. Lopoliths are generally concordant with the intruded strata with dike or funnel-shaped feeder bodies below the body. Lopoliths typically consist of large ultramafic to mafic layered intrusions that range in age from Archean to Eocene. [Wikipedia]
Very little is known about the lower mantle apart from that it appears to be relatively seismically homogeneous. The lower mantle is under tremendous pressure and therefore has a higher viscosity than the upper mantle.[Wikipedia]
The mantle is a highly viscous layer between the crust and the outer core. Earth's mantle is an approximately 2,970 km thick (~1,800 mi) rocky shell that constitutes approximately 84 percent of Earth's volume. [Wikipedia]
The mesosphere refers to the mantle in the region between the asthenosphere and the outer core. The upper boundary is defined as the sharp increase in seismic wave velocities and density at a depth of 660 km. [Wikipedia]
The boundary between the crust and mantle is conventionally placed at the Mohorovi_i_ discontinuity, a boundary defined by a contrast in seismic velocity. [Wikipedia]
The liquid outer core surrounds the inner core and is believed to be composed of iron mixed with nickel and trace amounts of lighter elements. [Wikipedia]
Seismic Zones are broad elongated regions along a fault line where earthquakes take place. [Wikipedia]
[Pluton] Igneous intrusion - A sill is a tabular pluton that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock. The term sill is synonymous with concordant intrusive sheet. This means that the sill does not cut across preexisting rocks, in contrast to dikes, which do cut across older rocks. [Wikipedia]
Transitional crust is crust that is thinned by the upwelling of mantle. [Wikipedia]
The mantle is divided into sections based upon results from seismology. The upper mantle is the region from 33–410 km (20 to 254 miles). The upper part of the mantle is composed mostly of peridotite, a rock denser than rocks common in the overlying crust. [Wikipedia]
The uppermost mantle plus overlying crust are relatively rigid and form the lithosphere, an irregular layer with a maximum thickness of perhaps 200 km. [Wikipedia]
Back-arc basins (or retro-arc basins) are geologic features, submarine basins associated with island arcs and subduction zones. They are found at some convergent plate boundaries, presently concentrated in the Western Pacific ocean. [Wikipedia]
Flysch is a sequence of sedimentary rocks that is deposited in a deep marine facies in the foreland basin of a developing orogen. Flysch is formed under deep marine circumstances, in a quiet and low-energetic depositional environment. [Wikipedia]
A forearc is a depression (basin) in the sea floor located between a subduction zone and an associated volcanic arc. It is typically filled with sediments from the adjacent landmass and the island arc in addition to trapped oceanic crustal material. [Wikipedia]
A foreland basin is a depression that develops adjacent and parallel to a mountain belt. Foreland basins form because the immense mass created by crustal thickening associated with the evolution of a mountain belt causes the lithosphere to bend, by a process known as lithospheric flexure. [Wikipedia]
Intra-arc basins are basins that occur between Fore-arc basins and back-arc basins [Wikipedia]
Intracratonic basins are formed by fluvial sedimentation of an intracratonic area which has undergone sediment sag-loading. [Wikipedia]
Peripheral (Pro) foreland basins occur on the plate that is subducted or underthrust during plate collision (i.e. the outer arc of the orogen).
Retroarc (Retro) foreland basins occur on the plate that overrides during plate convergence or collision (i.e. situated behind the magmatic arc that is linked with the subduction of oceanic lithosphere). [Wikipedia]
Successor basins arise from shifting and merging of fore arc, back-arc and intra-arc basins. Basins or sequences that overlap terrane boundaries. [Wikipedia]
Transpression basins are formed during oblique collision of tectonic plates and during non-orthogonal subduction. [Wikipedia]
Transtension basins are oblique tensional environments where stretching takes place. [Wikipedia]
An inclusion of an earlier rock that is prevented from further reaction in a later rock by a rim of reaction products.
a crystal of an earlier rock that is prevented from further reaction in a later rock by a rim of reaction products
the enclosed crystal in a poikolitic texture
Orthomatrix in matrix supported sedimentary rock.
A cluster of ferromagnesian minerals in an igneous rock, from several centimeters to decimeters in diameter, that may be a segregation or an altered xenolith.
Constituent occurs as a concentric envelope enclosing another constituent. Corona is a non-genetic term.
A corona formed by a secondary mineral around an orginal igneous crystal, formed by modification of the crystal by the corrosive action of its parent magma.
Constituent forms an interconnected network of discernible crystals.
An oversized stone in laminated sediment that depresses the underlying laminae and may be covered by -draped laminae. Most dropstones originate through ice-rafting; other sources are floating tree roots and kelp holdfasts....
A type of matrix consisting of inhomogeneous interstitial materials grown in originally open interstices during diagenesis, but lacking the homogeneity and clear textural evidence of pore-filling needed to classify as phyllosilicate cement.
Constituent is a clast that has no visible contacts with other clasts. Interpreted to be largely or completly immersed in matrix or cement.
Constituent forms a rigid arrangement of particles that support one another at their points of contact...constituting a mechanically firm structure capable of supporting open pore spaces, although interstices may be occupied by cement or matrix
Constituent forms an interconnected network of material enclosing other constituents that are disguished by larger grain size.
A fragment of older material within an igneous rock to which it may or may not be genetically related.
Constituent is distributed through the material between other constituent particles
A constituent with irregular distribution and geometry, as in pseudobreccia or patch migmatite.
Corona that consists of concentric bands with radial fibrous texture.
A thin sheet compositionally distinct from the surrounding material, related to primary genesis of rock, e.g. sedimentary layers, metamorphic segregation.
Constituent forms finer-grained material interstitial to a framework constituent. ‘The finer-grained material enclosing, or filling the interstices between, the larger grains or particles of a sediment or sedimentary rock....The term refers to the relative size and disposition of the particles, and no particular particle size is implied’ (Jackson, 1997, p. 393). May be classifiable into orthomatrix, protomatrix, epimatrix, pseudomatrix, and unclassified matrix.
constituent occurs as a collection of particles that are characterized by average properties of the individual particles
Constituent occurs as crystals that poikilitically enclose crystals of other phases in an igneous rock.
A type of matrix consisting of recrystallized detrital lutum (clay fraction, less than 2 micron) or protomatrix.
Constituent crystallized in crystallographic continuity with some other mineral constituent, typically quartz or calcite. In a clastic rock, commonly forms cement as well, but this should be represented using two role attribute links, 'overgrowth' and cement, because overgrowth does not necessarily imply cement.
any crystal in an igneous or metamorphic rock that is sgnificantly larger than the surounding groundmass. May be a phenocryst, xenocryst, porphyroblast or porphyroclast.
a relatively large and conspicuous fragment in a sediment or sedimentary rock
A phenocryst is a relatively large and usually conspicuous crystal distinctly larger than the grains of the rock groundmass of a porphyritic igneous rock. Phenocrysts often have euhedral forms either due to early growth within a magma or by post-emplacement recrystallization. [Wikipedia]
Constituent occurs as crystals formed by metamorphic crystallization, set in a finer-grained groundmass.
Relict crystal in metamorphic rock, in groundmass of relatively finer-grained material. Connotes that groundmass is result of tectonic reduction in grain size.
A type of matrix consisting of un-recrystallized detrital clayey lutum (clay fraction, less than 2 micron) in weakly consolidated rocks.
A type of matrix consisting of soft deformable framework grains that are squeezed and flattened between stronger framework grains.
A constituent that occupies space between individual grains of a consolidated sedimentary rock, and binds the grains together as a rigid, coherent mass; it may be derived from the sediment or its entrapped waters, or it may be brought in by solution from outside sources. Material is usually chemically precipitated (Jackson, 1997, p. 103). Distinguished from matrix by clearly secondary origin and generally monomineralic charactera
A hard, compact mass or aggregate of mineral matter, normally subsperical but commonly oblate, disc-shaped or irregular. Formed by precipitation of mineral from solution in the pores of a granular rock, localized around a nucleus or center, to define a discrete, sharply separated object. Size ranges from cm to decimeter for application as a compoundMaterialConstituentPart; larger concretions should be considered GeologicUnit parts.
Constituent occurs in a structural configuration integral to the rock, such as layering, veinlets, overgrowths. The 'material' composition of these parts will often be other rock materials, not minerals, and 'ParticleGeometryDescription' associated with these describes the geometry of the constituent, not the particles the it is made of. These roles are mostly useful for RockMaterial descriptions that apply to individual samples, because their distribution is unlikely to be pervasive enought to be considered characteristic of a large mass of material.
Thin sheet of material intruded into the rock. May be hydrothermal, magmatic, or sedimentary.
A distinction of whether the continental margins are active (subducting). [Wikipedia]
The continental crust is typically from 30 km (20 mi) to 50 km (30 mi) thick, and it is mostly composed of less dense rocks, such as granite, than is the oceanic crust. The continental crust has an average composition similar to that of the igneous rock, andesite.[Wikipedia]
[Mechanical or Seismic Definition of Structure] In the Earth, the lithosphere includes the crust and the uppermost mantle, which constitute the hard and rigid outer layer of the planet. The [Wikipedia]
The continental margin is the zone of the ocean floor that separates the thin oceanic crust from thick continental crust. [Wikipedia]
The extensive central cratons of continents may consist of both shields and platforms, and the crystalline basement. A platform is that part of the craton for which the basement is overlain by horizontal or subhorizontal sediments. [Wikipedia]
A long, narrow fissure in the Earth marking a zone of the lithosphere that has become thinner due to extensional forces associated with plate teconics. Continental rifts are thousands of kilometers in length and hundreds of kilometers in width, and they are associated with normal faults and with grabens. [FreeDictionary]
A craton is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. Some are over two billion years old. Cratons are generally found in the interiors of continents and are characteristically composed of ancient crystalline basement crust of lightweight felsic igneous rock such as granite. They have a thick crust and deep roots that extend into the mantle beneath to depths of 200 km. [Wikipedia]
The extensive central cratons of continents may consist of both shields and platforms, and the crystalline basement. A shield is that part of a craton in which the usually Precambrian basement rocks crop out extensively at the surface. [Wikipedia]
A distinction of whether the continental is on a stable paltform, i.e., over millions of years. [Wikipedia]
In geology, a supercontinent is a land mass comprising more than one continental core, or craton. The assembly of cratons and accreted terranes that form Eurasia qualifies as a supercontinent today.
In a Back-arc basin the arc axis is the line where spreading occurs on the overlying plate of the subduction zone. [Wikipedia]
A forearc is a depression in the sea floor located between a subduction zone and an associated volcanic arc. It is typically filled with sediments from the adjacent landmass and the island arc in addition to trapped oceanic crustal material. [Wikipedia]
The remnant arc is what is left on the rear side of the speading zone as athe basin broadens. [Wikipedia]
An imaginary surface representing the static head of groundwater and defined by the level to which water will rise in a tightly cased well.
A boundary between the saturated flow field and the atmosphere along which groundwater discharges, either by evaporation or movement ‘downhill’ along the land surface or in a well as a thin film in response to the force of gravity.
The water table or phreatic surface is the surface where the water pressure is equal to atmospheric pressure. A sustainable amount of water within a unit of sediment or rock, below the water table, in the phreatic zone is called an aquifer. The ability of the aquifer to store groundwater is dependent on the primary and secondary porosity and permeability
In physical geography, a channel is the physical confine of a river, slough or ocean strait consisting of a bed and banks. A channel is also the natural or man-made deeper course through a reef, bar, bay, or any shallow body of water. It is especially used as a Nautical term to mean the dredged and marked lane of safe travel which a cognizant governmental entity guarantees to have a minimum depth across its specified minimum width to all vessels transiting a body of water. The term not only includes the deep-dredged ship-navigable parts of an estuary or river leading to port facilities, but also to lesser channels accessing boat port-facilities such as marinas. When dredged channels traverse bay mud or sandy bottoms, repeated dredging is often necessary because of the unstable subsequent movement of benthic soils.
An estuary is a semi-enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries are often associated with high rates of biological productivity. An estuary is where the river meets the sea. An estuary is typically the tidal mouth of a river, and estuaries are often characterized by sedimentation or silt carried in from terrestrial runoff and, frequently, from offshore. They are made up of brackish water. Estuaries are more likely to occur on submerged coasts, where the sea level has risen in relation to the land; this process floods valleys to form rias and fjords. These can become estuaries if there is a stream or river flowing into them.
A fjord (or fiord) is a long, narrow estuary with steep sides, made when a glacial valley is filled by rising sea water levels. The seeds of a fjord are laid when a glacier cuts a U-shaped valley through abrasion of the surrounding bedrock by the sediment it carries. Many such valleys were formed during recent ice age when the sea was at a much lower level than it is today. At the end of the ice age, the climate warmed up again and glaciers retreated. Sea level rose due to an influx of water from melting ice sheets and glaciers around the world (it rose over 100 m after the last ice age), inundating the vacated valleys with seawater to form fjords.
An inlet is a narrow body between islands or leading inland from a larger body of water, often leading to an enclosed body of water, such as a sound, bay, lagoon or marsh. In sea coasts an inlet usually refers to the actual connection between a bay and the ocean and is often called an entrance.
A lagoon is a body of comparatively shallow salt or brackish water separated from the deeper sea by a shallow or exposed sandbank, coral reef, or similar feature. Thus, the enclosed body of water behind a barrier reef or barrier islands or enclosed by an atoll reef is called a lagoon. Lagoon refers to both coastal lagoons formed by the build-up of sandbanks or reefs along shallow coastal waters, and the lagoons in atolls, formed by the growth of coral reefs on slowly sinking central islands. Lagoons that are fed by freshwater streams are also called estuaries
In geography, a marsh, or morass, is a type of wetland which is subject to frequent or continuous inundation. Typically a marsh features grasses, rushes, reeds, typhas, sedges, and other herbaceous plants (possibly with low-growing woody plants) in a context of shallow water. A marsh is different from a swamp, which has a greater proportion of open water surface, and is generally deeper than a marsh. In North America, the term swamp is used for wetland dominated by trees rather than grasses and low herbs
Peat forms in wetlands or peatlands, variously called bogs, moors, muskegs, pocosins, mires, and peat swamp forests
A river is a natural waterway that transits water through a landscape from higher to lower elevations called divides. The divide determines which way a river will flow. It is an integral component of the water cycle. The water within a river is generally collected from precipitation through surface runoff, groundwater recharge (as seen at baseflow conditions / during periods of lack of precipitation) and release of stored water in natural reservoirs, such as a glacier
A spring is a point where groundwater flows out of the ground, and is thus where the aquifer surface meets the ground surface. Dependent upon the constancy of the water source (rainfall or snowmelt that infiltrates the earth), a spring may be ephemeral (intermittent) or perennial (continuous).
A stream is a body of water with a current, confined within a bed and banks. Streams are important as conduits in the water cycle, instruments in aquifer recharge, and corridors for fish and wildlife migration. The biological habitat in the immediate vicinity of a stream is called a riparian zone. Given the status of the ongoing Holocene extinction event, streams play an important corridor role in connecting fragmented habitats and thus in conserving biodiversity. Stream is also an umbrella term used in the scientific community for all flowing natural waters, regardless of size. The study of streams and waterways in general is known as surface hydrology and is a core element of environmental geography
A swamp is a wetland that features temporary or permanent inundation of large areas of land by shallow bodies of water, generally with a substantial number of hammocks, or dry-land protrusions, and covered by aquatic vegetation, or vegetation that tolerates periodical inundation.The water of a swamp may be fresh water or salt water. A swamp is also generally defined as having no substantial peat deposits.
In physical geography, a wetland is an environment at the interface between truly terrestrial ecosystems and aquatic systems making them inherently different from each other yet highly dependent on both. In essence, wetlands are ecotones. Wetlands often host considerable biodiversity and endemism. The US Army Corps of Engineers and the US Environmental Protection Agency jointly define wetlands as: Those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas.
Aeolian (or Eolian or Æolian) processes pertain to the activity of the winds and more specifically, to the winds' ability to shape the surface of the Earth and other planets. Winds may erode, transport, and deposit materials, and are effective agents in regions with sparse vegetation and a large supply of unconsolidated sediments. [Wikipedia]
A desert is a landscape form or region that receives very little precipitation.
A dune is a hill of sand built by eolian processes. Dunes are subject to different forms and sizes based on their interaction with the wind. Most kinds of dune are longer on the windward side where the sand is pushed up the dune, and a shorter slip face in the lee of the wind. The valley or trough between dunes is called a slack. A dune field is an area covered by extensive sand dunes. Large dune fields are known as ergs.
A beach, or strand, is a geological landform consisting of loose rock particles - such as sand, gravel, shingle, pebbles, cobble - or even shell fragments, along the shoreline of a body of water. Beaches occur along coastal areas, where wave or current action deposits and reworks sediments, or at the margin of land along a lake or river subject to erosion caused by rainfall. Beaches are not necessarily found in conjunction with salt water, such as the ocean, in all instances. A seashore beach is merely one type of beach but it is the most commonly associated with the perception of the word beach.
A delta is a landform where the mouth of a river flows into an ocean, sea, desert, estuary, lake or another river. It builds up sediment outwards into the flat area which the river's flow encounters (as a deltaic deposit) transported by the water and set down as the currents slow. Deltaic deposits of larger, heavily-laden rivers are characterized by the main channel dividing amongst often substantial land masses into multiple streams known as distributaries. These divide and come together again to form a maze of active and inactive channels.
The intertidal zone, also known as the littoral zone, in marine aquatic environments is the area of the foreshore and seabed that is exposed to the air at low tide and submerged at high tide, for example, the area between tide marks.
A riparian zone is the interface between land and a flowing surface water body. Plant communities along the river margins are called riparian vegetation, characterized by hydrophilic plants. Riparian zones are significant in ecology, environmental management, and civil engineering due to their role in soil conservation, their biodiversity, and the influence they have on aquatic ecosystems. Riparian zones occur in many forms including grassland, woodland, wetland or even non-vegetative. In some regions the terms riparian woodland, riparian forest, riparian buffer zone or riparian strip are used to characterize a riparian zone.
A shoal is a somewhat linear landform within or extending into a body of water, typically comprised of sand, silt or small pebbles. Alternatively termed sandbar or sandbank, a bar is characteristically long and narrow (linear) and develops where a stream or ocean current promote deposition of granular material, resulting in localized shallowing (shoaling) of the water. Bars can appear in the sea, in a lake, or in a river. Alternatively a bar may separate a lake from the sea, as in the case of an ayre. They are typically composed of sand, although could be of any granular matter that the moving water has access to and is capable of shifting around (for example, soil, silt, gravel, cobble, shingle, or even boulders). The grain size of the material comprising a bar is related to the size of the waves or the strength of the currents moving the material, but the availability of material to be worked by waves and currents is also important.
A shore or shoreline is the fringe of land at the edge of a large body of water, such as an ocean, sea, or lake.
The process of depositing soil or sediments by a river or other running water. [Wikipedia]
A canyon, or gorge, is a deep valley between cliffs often carved from the landscape by a river. Most canyons were formed by a process of long-time erosion from a plateau level. [Wikipedia]
A catchment, or drainage basin, is an extent of land where water from precipitation drains into a body of water [Wikipedia]
A trench is a type of excavation or depression in the ground. Trenches are generally defined by being deeper than they are wide (as opposed to a wider gully or ditch), and by being narrow compared to their length (as opposed to a simple hole). Trenches are a natural feature in many landscapes. Some are created by rivers in flow (which may have long since fallen dry), others are features created by geological movement, such as oceanic trenches. The latter form is relatively deep, linear and narrow, and is formed by plate subduction. [Wikipedia]
A valley (also called a vale, dale, glen or strath and near or in Appalachia, a draw) is a depression with predominant extent in one direction. [Wikipedia]
A watershed refers to a divide that separates one drainage area from another drainage area. However, in the US and Canada, the term is often used to mean a drainage basin or catchment area itself. [Wikipedia]
A continent is one of several large landmasses. [Wikipedia]
Field (agriculture), an area of land used to cultivate crops, or to keep livestock [Wikipedia]
Land cover is the physical material at the surface of the earth. Land covers include grass, asphalt, trees, bare ground, water, etc. [Wikipedia]
A landform comprises a geomorphological unit, and is largely defined by its surface form and location in the landscape, as part of the terrain, and as such, is typically an element of topography. Landforms are categorised by features such as elevation, slope, orientation, stratification, rock exposure, and soil type. They include berms, mounds, hills, cliffs, valleys, rivers and numerous other elements.
A landscape comprises the visible features of an area of land, including physical elements such as landforms, living elements of flora and fauna, abstract elements such as lighting and weather conditions, and human elements, for instance human activity or the built environment. Landscape may also signify the objects around one in a building.
A thin, almost knife-like, ridge of rock which is typically formed when two glaciers erode parallel U-shaped valleys.
An amphitheatre-like valley head, formed at the head of a valley glacier by erosion.
A long winding ridge of stratified sand and gravel, examples of which occur in glaciated and formerly glaciated regions.
An irregularly shaped hill or mound composed of sand, gravel and till that accumulates in a depresson on a retreating glacier, and is then deposited with further melting.[Wikipedia]
Any glacially formed accumulation of unconsolidated glacial debris (soil and rock) which can occur in currently glaciated and formerly glaciated regions.
A fan-shaped body of sediments deposited by braided streams from a melting glacier. Sediment locked within the ice of the glacier gets transported by the streams of meltwater and deposits on the outwash plain at the terminus of the glacier.
Rock glaciers are distinctive geomorphological landforms of blocky detritus which may extend outward and downslope from talus cones or from glaciers or the terminal moraines of glaciers. [Wikipedia]
A glacial outwash plain formed of sediments deposited by meltwater at the terminus of a glacier.
A land surface characterised by very irregular surfaces of marshy hollows and small hummocks formed as ice-rich permafrost thaws.
An extensive flat plain of glacial till that forms when a sheet of ice becomes detached from the main body of a glacier and melts in place depositing the sediments it carried.
Alpine region is one above the tree line. [Wikipedia]
A hill is a landform that extends above the surrounding terrain, in a limited area. Hills often have a distinct summit, although in areas with scarp/dip topography a hill may refer to a particular section of scarp slope without a well-defined summit (e.g. Box Hill). A hillock is a small hill. [Wikipedia]
A slope formed at the base of a steeper slope, made of fallen and disintegrated materials.
The shady (usually poleward) side of a mountain.
Are neighboring ridges on different tectonic plates which have similar seismic characteristics. ‘Based on similar seismic velocity gradients of the lavas of the Carnegie, Cocos and Malpelos Ridges there is evidence that the hotspot activity has been the result of a single long mantle melt rather than multiple periods of activity and dormancy.’ [Wikipedia]
In plate tectonics, a convergent boundary or convergent plate boundary, also known as a destructive plate boundary (because of subduction), is an actively deforming region where two (or more) tectonic plates or fragments of lithosphere move toward one another and collide and where crust is being destroyed. [Wikipedia]
In plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a linear feature that exists between two tectonic plates that are moving away from each other and new crust is being formed. [Wikipedia]
A flood basalt or trap basalt is the result of a giant volcanic eruption or series of eruptions that coats large stretches of land or the ocean floor with basalt lava. Flood basalts have occurred on continental scales (large igneous provinces) in prehistory, creating great plateaus and mountain ranges. [Wikipedia]
Are where similar plant and animal fossils are found around different continent shores, suggesting that they were once joined. [Wikipedia]
A fracture zone is a linear oceanic feature--often hundreds, even thousands of kilometers long--resulting from the action of offset mid-ocean ridge axis segments. They are a consequence of plate tectonics. Lithospheric plates on either side of an active transform fault move in opposite directions; here, strike-slip activity is possible. Fracture zones extend past the transform faults, away from the ridge axis; seismically inactive (because both plate segments are moving in the same direction), they display evidence of past transform fault activity.
An Ophiolite is a section of the Earth's oceanic crust and the underlying upper mantle that has been uplifted or emplaced to be exposed within continental crustal rocks. [Wikipedia]
A location where belts of high pressure, low temperature metamorphism on the oceanic side are associated with belts of high pressure, high temperature metamorphism on the continent side. [Wikipedia]
The location where two plates meet is called a plate boundary. it is often a broad zone where the plate interactions are not well understood. [Wikipedia]
A rift is a place where the Earth's crust and lithosphere are being pulled apart[1] and is an example of extensional tectonics. [Wikipedia]
A rift valley is a linear-shaped lowland between highlands or mountain ranges created by the action of a geologic rift or fault. [Wikipedia]
Stress regimes are shear zones. A shear zone or shear is a wide zone of distributed shearing in rock. Typically this is a type of fault but it may be difficult to place a distinct fault plane into the shear zone. Shear zones may form zones of much more intense foliation, deformation, and folding. [Wikipedia]
A subduction zone is an area on Earth where two tectonic plates move towards one another and subduction occurs. [Wikipedia]
There is increasing evidence that most ophiolites are generated when subduction begins and thus represent fragments of fore-arc lithosphere. This led to introduction of the term ‘supra-subduction zone’ (SSZ) ophiolite in the 1980s to acknowledge that some ophiolites are more closely related to island arcs than ocean ridges. [Wikipedia]
A suture is where a fragment of crustal material is accreted to crust lying on another plate. [Wikipedia]
A thrust fault system is one in which the higher side of the fault moves upward. [Wikipedia]
A transform plate boundary is where two lithospheric plates slide past each other and where crust is neither produced or destroyed. [Wikipedia]
Transpression regimes are formed during oblique collision of tectonic plates and during non-orthogonal subduction. [Wikipedia]
Transtension regimes are oblique tensional environments where stretching takes place. [Wikipedia]
The Galapagos Triple Junction is a geological area in the eastern Pacific Ocean several hundred miles west of the Galapagos Islands where three tectonic plates - the Cocos Plate, the Nazca Plate and the Pacific Plate - meet. [Wikipedia]
A volcano constructed by the ejection of debris and lava flows from a central point, forming a more or less symmetrical volcano.
A volcano that consists of a complex of two or more vents, or a volcano that has an associated volcanic dome, either in its crater or on its flanks.
In geology, geothermal refers to heat sources within the planet. Strictly speaking, geo-thermal necessarily refers to the Earth but the concept may be applied to other planets. Geothermal is technically an adjective (e.g., geothermal energy) but in U.S. English the word has attained frequent use as a noun (otherwise expressed as g. heat, g. source, or geotherm). The planet's internal heat was originally generated during its accretion, due to gravitational binding energy, and since then additional heat has continued to be generated by the radioactive decay of elements such as uranium, thorium, and potassium. The heat flow from the interior to the surface is only 1/20,000 as great as the energy received from the Sun.
In geology, a hotspot is a location on the Earth's surface that has experienced active volcanism for a long period of time. [Wikipedia]
Where this association of flood basalts with continental rifting is observed, it is not uncommon to find linear chains of volcanic islands [Wikipedia]
A volcano built by a single eruption.
A volcano composed of both lava flows and pyroclastic material.
A doming or small mound on the crest of a lava flow caused by pressure due to the difference in the rate of flow between the cooler crust and the more fluid lava below.
Island arcs that develop along the edges of a continent (for example, large parts of the Andes/ Central American/ Canadian mountain chain) may be known as a volcanic arc or volcanic chain. [Wikipedia]
A volcanic field is a spot of the earth's crust that is prone to localized volcanic activity. They usually contain 10 to 100 volcanoes, such as cinder cones and are usually in clusters. Lava flows may also occur. They may occur as a monogenetic volcanic field or a polygenetic volcanic field. [Wikipedia]
A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash, and gases to escape from below the surface. Volcanic activity involving the extrusion of rock tends to form mountains or features like mountains over a period of time. [Wikipedia]
The aphotic zone is the portion of a lake or ocean where there is little or no sunlight. It is formally defined as the depths beyond which less than 1% of sunlight penetrates. Consequently, bioluminescence is essentially the only light found in this zone. Most food comes from dead organisms sinking to the bottom of the lake or ocean from other zones. The depth of the aphotic zone can be greatly affected by such things as turbidity and the season of the year. The aphotic zone underlies the photic zone, which is that portion of the ocean directly affected by sunlight.
The depth range, where it exists, between the bottom of the oceanic surface mixed layer and the thermocline, usually at a depth between 30 and 80 m.
Benthic means anything associated with or happening on the bottom of a body of water. The Benthic Zone of the ocean is the bottom ocean zone ranging from the deepest parts of the ocean to the tidal affected areas. The most productive region of the benthic zone is the area over the continental margin, which is unaffected by the tides.
The demersal zone is the part of the sea or ocean (or deep lake) comprising the water column that is near to (and is significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of the larger profundal zone.
In oceanography, a Halocline is a strong, vertical salinity gradient. Because salinity (in concert with temperature) affects the density of seawater, it can play a role in its vertical stratification.
The limnetic zone is the well-lit, open surface waters farther from shore in a lake. It is surrounded by the littoral zone and above the profundal zone
The pelagic zone is the part of the open sea or ocean that is not near the coast.
The photic zone or euphotic zone is the depth of the water whether in a lake or an ocean, that is exposed to sufficient sunlight for photosynthesis to occur. The depth of the euphotic zone can be greatly affected by seasonal turbidity.
A polynya is any non-linear area of open water surrounded by sea ice. It is now used as geographical term for areas of sea in Arctic or Antarctic regions which remain unfrozen for much of the year.
The profundal zone is a deep zone of a body of water, such as an ocean or a lake, located below the range of effective light penetration. This is typically below the thermocline, the vertical zone in the water through which temperature drops rapidly. The lack of light in the profundal zone determines the type of biological community that can live in this region, which is distinctly different from the community in the overlying waters. The profundal zone is part of the aphotic zone.
A pycnocline is a layer across which there is a rapid change in water density with depth. In freshwater environments such as lakes this density change is primarily caused by water temperature, while in seawater environments such as oceans the density change may be caused by changes in water temperature and/or salinity
The thermocline (sometimes metalimnion) is a layer within a body of water or air where the temperature changes rapidly with depth.
The western part of the subpolar gyre in the deep (western) part of the Bering Sea.
A surface current flowing northward along the central axis of the Yellow Sea.
A hydrothermal vent is a fissure in a planet's surface from which geothermally heated water issues. Hydrothermal vents are commonly found near volcanically active places, areas where tectonic plates are moving apart, ocean basins, and hotspots.
A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. This uplifting of the ocean floor occurs when convection currents rise in the mantle beneath the oceanic crust and create magma where two tectonic plates meet at a divergent boundary. The mid-ocean ridges of the world are connected and form a single global mid-oceanic ridge system that is part of every ocean, making the mid-oceanic ridge system the longest mountain range in the world.
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water yet shallow enough to be a hazard to ships. Many reefs result from abiotic processes—deposition of sand, wave erosion planning down rock outcrops, and other natural processes—but the best-known reefs are the coral reefs of tropical waters developed through biotic processes dominated by corals and calcareous algae
A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface (sea level), and thus is not an island. These are typically formed from extinct volcanoes, that rise abruptly and are usually found rising from a seafloor of 1,000 - 4,000 meters depth. They are defined by oceanographers as independent features that rise to at least 1,000 meters above the seafloor. The peaks are often found hundreds to thousands of meters below the surface, and are therefore considered to be within the deep sea.[1] An estimated 30,000 seamounts occur across the globe, with only a few having been studied. However, some seamounts are also unusual.
A submarine canyon is a steep-sided valley on the sea floor of the continental slope. Many submarine canyons are found as extensions to large rivers; however there are many that have no such association. Canyons cutting the continental slopes have been found at depths greater than 2 km below sea level. They are formed by powerful turbidity currents, volcanic and earthquake activity. Many submarine canyons continue as submarine channels across continental rise areas and may extend for hundreds of kilometers.
In environments containing permafrost, the active layer is the top layer of soil that thaws during the summer and freezes again during the autumn.
Gelisols are soils of very cold climates which are defined as containing permafrost within two metres of the soil surface. The word Gelisol comes from the Latin gelare meaning to freeze, a reference to the process of cryoturbation that occurs from the alternating thawing and freezing characteristic of Gelisols.
Any variable considered as a function of other variables, the latter being called independent.
In common usage, a dimension is a parameter or measurement used to describe some relevant characteristic of an object. The most commonly used dimensions are the parameters describing the size of an object: length, width, and height, but dimensions can also be other physical parameters such as the mass and electric charge of an object, or even, in a context where cost is relevant, an economic parameter such as its price.
Shares data model with HDF5.
A conversion from one coordinate system to another, for example to a common spatial grid.
An equation is a mathematical statement, in symbols, that two things are exactly the same (or equivalent). [Wikipedia]
In mathematics, the concept of a relation is a generalization of 2-place relations, such as the relation of equality, less than, greater than, etc.. [Wikipedia]
Any quantity, such as force, velocity, or acceleration, that has both magnitude and direction at each point in space, as opposed to a scalar that has magnitude only.
A point in the range of a function at which it is undefined or not continuous [Wiktionary]
An operation is an action or procedure which produces a new value from one or more input values. [Wikipedia]
A line drawn through all geographic points at which the thickness of a given atmospheric layer is the same; an isopleth of thickness.
As originally formulated, a statement of the conservation of energy (per unit mass) for an inviscid fluid in steady motion.
Attenuation of a beam of light by an optically homogeneous (transparent) medium.
A law describing the relationship of the horizontal wind direction in the atmosphere to the pressure distribution.
A relationship between radar reflectivity factor Z (mm6 m-3) and rain rate R (mm h-1).
Optics is a branch of physics that describes the behavior and properties of light and the interaction of light with matter. Optics explains optical phenomena
An approximation to the dynamical equations of motion whereby density is assumed to be constant except in the buoyancy term of the vertical velocity equation.
A set of different forecasts all valid at the same forecast time(s).
A forecast of weather conditions for a period extending beyond three or more days from the day of issuance.
An imaginary volume of fluid to which may be assigned various thermodynamic and kinematic quantities.
A simulation approach to studying the chemical evolution of a (natural) system.
This concept is of space as an independent variable
Curve in space tracing the points successivley occupied by a particle in motion
Coordinate System with its origin on the axis of the Earth and fixed with respect to the stars.
This concept is of time as an independent variable
An acid as a compound which donates a hydrogen ion (H+) to another compound (called a base). [Wikipedia]
A base is most commonly thought of as an aqueous substance that can accept hydrogen ions. [Wikipedia]
Motions describing an equlibrium between pressure gradient force, Coriolis force and the turbulent drag force.
Said of two or more liquids that are mutually soluble (i.e. they will dissolve in each other) (McGraw-Hill, 1974). The chemical property of two or more phases that, when brought together, have the ability to mix and form one phase (after AGI, 1980).
A system or flow that evolves slowly in time compared to the rotation period of the earth, has a length scale of the deformation radius or larger, and undergoes only limited vertical excursions.
A small spherical particle of any liquid; in meteorology, particularly a water droplet.
Pertaining to atmospheric phenomena having horizontal scales ranging from a few to several hundred kilometers, including thunderstorms, sordil lines, fronts, precipitation bands in tropical and extratropical cyclones, and topographically generated weather systems such as mountain waves and sea and land breezes. From a dynamical perspective, this term pertains to processes with timescales ranging from the inverse of the Brunt?V?is?l? frequency to a pendulum day, encompassing deep moist convection and the full spectrum of inertio-gravity waves but stopping short of synoptic-scale phenomena, which have Rossby numbers less than 1.
Electromagnetic radiation of shorter wavelength than visible radiation but longer than x-rays.
A complex system is a system composed of interconnected parts that as a whole exhibit one or more properties (behavior among the possible properties) not obvious from the properties
In mechanics, a state in which the vector sum of all forces, that is, the acceleration vector, is zero. In hydrodynamics, it is usually further required that a steady state exist throughout the atmospheric or fluid model. The equilibrium may be stable or unstable with respect to displacements therefrom. See also hydrostatic equilibrium, geostrophic equilibrium, instability. 2. In thermodynamics, any state of a system that would not undergo change if the system were to be isolated.
The characteristic of a system if sufficiently small disturbances have only small effects, either decreasing in amplitude or oscillating periodically; it is asymptotically stable if the effect of small disturbances vanishes for long time periods.
property describing unstable conditions, such as in the atmosphere
A process in which a system does not interact with its surroundings by virtue of a temperature difference between them.
A moist-adiabatic process in which the liquid water that condenses is assumed to be removed as soon as it is formed, by idealized instantaneous precipitation.
Epochs are divided into ages [millions of years] [Wikipedia]
Supereons are divided into eons. [billions of years] [Wikipedia]
Periods are divided into epochs [tens of millions of years] [Wikipedia]
Eons are divided into eras [several hundred million years] [Wikipedia]
The subdivisions of geologic time. The table of geologic time spans are dates and nomenclature defined by the International Commission on Stratigraphy. [Wikipedia]
Eras are divided into periods. [Wikipedia]
The largest defined unit of time is the supereon, composed of eons.] [Wikipedia]
The most common of several names given toa significant decrease in sea surface temperature (‘cold events’) in the central and eastern equatorial Pacific. La Nina is the counterpart to the El Nino ‘warm event,’ and its spatial and temporal evolution in the equatorial Pacific is, to a considerable extent, the mirror image of El Nino, although La Nina events tend to be somewhat less regular in their behavior and duration.
The region of dense cloud near the core of a tropical cyclone.
When the direct radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and heat.