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CDIAC - Atmosphere Glossary Category: Meteorology and astronomy > Atmosphere Date & country: 13/09/2007, USA Words: 301

ablation (glacial)
All processes, which include melting, evaporation (sublimation), wind erosion, and calving (breaking off of ice masses), that remove snow or ice from a glacier or snowfield. The term also refers to the amount of snow or ice removed by these processes.

abscission
Shedding by a plant of its parts, such as leaves, flowers, fruits, or seeds. The process is regulated by the plant hormone abscisic acid.

absorption coefficient
A measure of the amount of radiant energy, incident normal to a planar surface, that is absorbed per unit distance or unit mass of a substance.

acclimation (acclimatization)
Change that occurs in an organism to allow it to tolerate a new environment.

accumulation (glacial)
All processes, which include snowfall, condensation, avalanching, snow transport by wind, and freezing of liquid water, that add snow or ice to a glacier, floating ice, or snow cover. The term also includes the amount of snow or other solid precipitation added to a glacier or snowfield by these processes.

acidity profile
The acid concentration in ice core layers as a function of depth as determined from electrical measurements. The magnitudes of some volcanic eruptions in the Northern Hemisphere have been estimated from the acidity of annual layers in ice cores taken in Greenland. This methodology is sometimes referred to as acidity signal or acidity record.

adaptation
The adjustment of an organism or population to a new or altered environment through genetic changes brought about by natural selection.

adiabatic process
A thermodynamic change of state of a system such that no heat or mass is transferred across the boundaries of the system. In an adiabatic process, expansion always results in cooling, and compression in warming.

advection
The predominately horizontal large-scale movement of air that causes changes in temperature or other physical properties. In oceanography, advection is the horizontal or vertical flow of sea water as a current.

aerosol
Particulate material, other than water or ice, in the atmosphere ranging in size from approximately 10x-3 to larger than 10x2 ´m in radius. Aerosols are important in the atmosphere as nuclei for the condensation of water droplets and ice crystals, as participants in various chemical cycles, and as absorbers and scatterers of solar radiation, thereby influencing the radiation budget of the earth-atmosphere system, which in turn influences the climate on the surface of the Earth.

agglomeration
In meteorology, the process by which precipitation particles grow larger by collision or contact with cloud particles or other precipitation particles.

Agung
Active volcano 10,380 ft (3,141 m) high in Bali, Indonesia. Last eruption was in 1964.

airborne fraction
The portion of CO2 released from all energy consumption and land use activities that remains in the atmosphere as opposed to the amounts absorbed by plants and oceans. How the world's total carbon is partitioned among the oceanic, terrestrial, and atmospheric pools is determined by complex biogeochemical and climatological interactions.

airborne particulates
Total suspended matter found in the atmosphere as solid pieces or liquid droplets. Airborne particulates include windblown dust, emissions from industrial processes, smoke from the burning of wood and coal, and the exhaust of motor vehicles.

airmass
A widespread body of in the atmosphere that gains certain meteorological or polluted characteristics while set in one location. The characteristics can change as it moves away.

albedo
The fraction of the total solar radiation incident on a body that is reflected by it.

Alfisols
An order of soils with a medium-to-high base supply, horizons of clay accumulation, and gray-brown surface horizons.

algae
Simple rootless plants that grow in sunlit waters in relative proportion to the amounts of nutrients available. They are food for fish and small aquatic animals.

algal blooms
Sudden spurts of algal growth that can indicate potentially hazardous changes in local water chemistry.

alkalinity
A pressure- and temperature-independent property of seawater that determines in part the carbon content of seawater. Carbonate alkalinity is the sum of the concen- tration of bicarbonate plus two times the concentration of the carbonate ions. Total alkalinity is the amount of acid required to bring seawater to a pH at which all dis- solved inorganic carbon becomes freely exchangeable. The alkalinity of the oceans is determined with potentiometric or normal titration techniques that detect and me…

altithermal period
A period of high temperature, particularly the one from 8000 to 4000 B.P. (before the present era), which was apparently warmer in summers, as compared with the present, and with the precipitation zones shifted poleward. Also called the hypsithermal period.

anadromous
Fish that spend their adult lives in the sea but swim upriver to freshwater spawning grounds to reproduce.

analog (climate)
A large-scale weather pattern of the past that is similar to a current situation in its essential characteristics.

Antarctic Ice Sheet
See ice sheet.

anthropogenic
Man made. Usually used in the context of emissions that are produced as the result of human activities.

anticyclone (high-pressure area)
An atmospheric high-pressure closed circulation with clockwise rotation in the Northern Hemisphere, counterclockwise in the Southern Hemisphere, and undefined at the Equator.

aragonite
A mineral species of calcium carbonate (CaCO3) with a crystal structure different from that of vaterite and calcite, which are the other two forms of CaCO3. It is precipitated from ocean surface waters mainly by organisms (e.g., coral) that use it to make their shells and skeletons.

Arctic haze
A persistent winter diffuse layer in the Arctic atmosphere whose origin may be related to long-range transport of midlatitude continental man-made pollutants.

atmosphere (An)
A standard unit of pressure representing the pressure exerted by a 29.92-in. column of mercury at sea level at 45 degrees latitude and equal to 1000 g/cm2.

atmosphere (The)
The envelope of air surrounding the Earth and bound to it by the Earth's gravitational attraction. Studies of the chemical properties, dynamic motions, and physical processes of this system constitute the field of meteorology.

atmospheric turbulence
A state of the flow of air in which apparently random irregularities occur in the air's instantaneous velocities, often producing major deformations of the flow.

atmospheric window
The spectral region between 8.5 and 11.0 microns where the atmosphere is essentially transparent to longwave radiation.

autotrophic
An organism that produces food from inorganic substances.

baroclinic model
A model of atmospheric circulation that, in contrast with barotropic models, does not constrain constant-pressure surfaces to coincide with constant-density surfaces.

basal sliding (basal slip)
The movement or speed of movement of a glacier on its bed.

bathymetry
The science of measuring ocean depths to determine the topography of the sea floor.

benthic organism (benthos)
A form of aquatic plant or animal life that is found on or near the bottom of a stream, lake, or ocean.

benthic region
The bottom layer of a body of water.

biogeochemical cycle
The chemical interactions among the atmosphere, biosphere, hydrosphere, and lithosphere.

biological productivity
The amount of organic matter, carbon, or energy content that is accumulated during a given time period.

biomass
The total dry organic matter or stored energy content of living organisms that is present at a specific time in a defined unit (community, ecosystem, crop, etc.) of the Earth's surface.

biosphere
The portion of Earth and its atmosphere that can support life. The part (reservoir) of the global carbon cycle that includes living organisms (plants and animals) and life- derived organic matter (litter, detritus). The terrestrial biosphere includes the living biota (plants and animals) and the litter and soil organic matter on land, and the marine biosphere includes the biota and detritus in the oceans.

biota
The animal and plant (fauna and flora) life of a given area.

bitumen
Dark, naturally occurring solid or semisolid substances composed mainly of a mixture of hydrocarbons with little oxygen, nitrogen, or sulfur.

buffer factor (Revelle factor)
The ratio of the instantaneous fractional change in the partial pressure of CO2 (pCO2) exerted by seawater to the fractional change in total CO2 dissolved in the ocean waters. The buffer factor relates the partial pressure of CO2 in the ocean to the total ocean CO2 concentration at constant temperature, alkalinity and salinity. The Revelle factor is a useful parameter for examining the distribution of CO2 between the atmosphere and the ocean, and measures in part the amount of CO2 that can be di…

calcrete
A surficial gravel and sand conglomerate cemented by calcium carbonate.

caliche
Also called hardpan; an opaque, reddish-brown-to-white calcareous material, which occurs in layers near the surface of stony soils in arid and semiarid areas.

Calvin cycle
The incorporation of CO2 into glucose by enzymatic reactions.

canopy
The branches and leaves of woody plants that are formed some distance above the ground.

carbon budget
The balance of the exchanges (incomes and losses) of carbon between the carbon reservoirs or between one specific loop (e.g., atmosphere - biosphere) of the carbon cycle. An examination of the carbon budget of a pool or reservoir can provide information about whether the pool or reservoir is functioning as a source or sink for CO2.

carbon cycle
All parts (reservoirs) and fluxes of carbon; usually thought of as a series of the four main reservoirs of carbon interconnected by pathways of exchange. The four reservoirs, regions of the Earth in which carbon behaves in a systematic manner, are the atmosphere, terrestrial biosphere (usually includes fresh water systems), oceans, and sediments (includes fossil fuels). Each of these global reservoirs may be subdivided into smaller pools ranging in size from individual communities or ecosystems …

carbon density
The amount of carbon per unit area for a given ecosystem or vegetation type, based on climatic conditions, topography, vegetative-cover type and amount, soils, and maturity of the vegetative stands.

carbon dioxide fertilization
Enhancement of plant growth or of the net primary production by CO2 enrichment that could occur in natural or agricultural systems as a result of an increase in the atmospheric concentration of CO2.

carbon dioxide reference gas
A mixture of a known quantity of CO2-in air or CO2-in-N2 used to calibrate carbon dioxide analyzers.

carbon flu
xThe rate of exchange of carbon between pools (reservoirs).

carbon isotope ratio
Ratio of carbon-12 to either of the other, less common, carbon isotopes, carbon- 13 or carbon-14.

carbon pool
The reservoir containing carbon as a principal element in the geochemical cycle.

carbon sink
A pool (reservoir) that absorbs or takes up released carbon from another part of the carbon cycle. For example, if the net exchange between the biosphere and the atmosphere is toward the atmosphere, the biosphere is the source, and the atmosphere is the sink.

carbon source
A pool (reservoir) that releases carbon to another part of the carbon cycle.

carbon-based resources
The recoverable fossil fuel (coal, gas, crude oils, oil shale, and tar sands) and biomass that can be used in fuel production and consumption.

catanadromous
Fish that swim downstream to spawn.

Chernozem (Tchernozem)
A major group of dark-colored zonal soils with a rich and deep humus horizon occurring in temperate-to-cool, subhumid climates.

chlorofluorocarbons
A family of inert nontoxic and easily liquified chemicals used in refrigeration, air conditioning, packaging, and insulation or as solvents or aerosol propellants. Because they are not destroyed in the lower atmosphere, they drift into the upper atmosphere where their chlorine components destroy ozone.

chloroplast
An organelle in the cells of green plants. It contains chlorophyll and functions in photosynthesis and protein synthesis.

clear cutting
A forest-management technique that involves harvesting all the trees in one area at one time.

climate
The statistical collection and representation of the weather conditions for a specified area during a specified time interval, usually decades, together with a description of the state of the external system or boundary conditions. The properties that characterize the climate are thermal (temperatures of the surface air, water, land, and ice), kinetic (wind and ocean currents, together with associated vertical motions and the motions of air masses, aqueous humidity, cloudiness and cloud water co…

climate change
The long-term fluctuations in temperature, precipitation, wind, and all other aspects of the Earth's climate. External processes, such as solar-irradiance variations, variations of the Earth's orbital parameters (eccentricity, precession, and inclination), lithosphere motions, and volcanic activity, are factors in climatic variation. Internal variations of the climate system also produce fluctuations of sufficient magnitude and variability to explain observed climate change through the feedback …

climate sensitivity
The magnitude of a climatic response to a perturbing influence. In mathematical modeling of the climate, the difference between simulations as a function of change in a given parameter.

climate signal
A statistically significant difference between the control and disturbed (see climate sensitivity) simulations of a climate model.

climate system
The five physical components (atmosphere, hydrosphere, cryosphere, lithosphere, and biosphere) that are responsible for the climate and its variations.

climate variation
The change in one or more climatic variables over a specified time.

climatic analog
A past climate situation in which changes similar to the present occurred. Used in making climatic projections.

climatic anomaly
The deviation of a particular climatic variable from the mean or normal over a specified time.

climatic optimum
The period in history from about 5000 to about 2500 B.C. during which surface air temperatures were warmer than at present in nearly all regions of the world. In the Arctic region, the temperature rose many degrees, and in temperate regions, the increase was 1.0 degrees - 1.7 degrees C. In this period, glaciers and ice sheets receded greatly, and the melt-water raised sea level by about 3 meters.

cloud
A visible mass of condensed water vapor particles or ice suspended above the Earth's surface. Clouds may be classified on their visible appearance, height, or form.

cloud albedo
Reflectivity that varies from less than 10 to more than 90% of the insolation and depends on drop sizes, liquid water content, water vapor content, thickness of the cloud, and the sun's zenith angle. The smaller the drops and the greater the liquid water content, the greater the cloud albedo, if all other factors are the same.

cloud feedback
The coupling between cloudiness and surface air temperature in which a change in surface temperature could lead to a change in clouds, which could then amplify or diminish the initial temperature perturbation. For example, an increase in surface air temperature could increase the evaporation; this in turn might increase the extent of cloud cover. Increased cloud cover would reduce the solar radiation reaching the Earth's surface, thereby lowering the surface temperature. This is an example of ne…

coastal zone
Lands and waters adjacent to the coast that exert an influence on the uses of the sea and its ecology or whose uses and ecology are affected by the sea.

composting
The natural biological decomposition of organic material in the presence of air to form a humus-like material.

continental crust
The layer of the Earth that lies under continents and the continental shelves. It ranges in thickness from 35 to 60 km. Its upper layer has a density of 2.7 g/cm3 and is composed of rocks that are rich in silica and alumina.

continental plate
A thick continental crust.

continental shelves
Those parts of the continent that are covered by water. They are several to more than 322 km wide and about 122 m deep. At the edges of the shelves, the continental slopes drop rapidly from 100 to 200 m to 3000 to 3700 m.

continental slopes
See continental shelves.

convection
Atmospheric or oceanic motions that are predominately vertical and that result in vertical transport and mixing of atmospheric or oceanic properties. Because the most striking meteorological features result if atmospheric convective motion occurs in conjunction with the rising current of air (i.e., updrafts), convection is sometimes used to imply only upward vertical motion.

convective adjustment
A numerical procedure applied in many atmospheric models to approximate the vertical nonradiative heat transport. This procedure adjusts the lapse rate whenever necessary so that some prescribed critical lapse rate is never exceeded.

convergence
The quasi-horizontal flow of a fluid toward a common destination from different directions. When waters of different origins come together at a point or along a line (convergence line), the denser water from one side sinks under the lighter water from other side. The ocean convergence lines are the polar, subtropical, tropical, and equatorial. Also see divergence.

Coriolis effect
The tendency for an object moving above the Earth to turn to the right in the Northern Hemisphere and to the left in the Southern Hemisphere relative to the Earth's surface. The effect arises because the Earth rotates and is not, therefore, an inertial reference frame.

cotyledon
A leaf or leaves of the embryos of seed plants. They can function in food storage and can become photosynthetic when the seed germinates.

crop water-use efficiency
A measure at the ecosystem level of how well plants use available water in growth. The grams of dry weight gained by plants during the growing season per unit land area are divided by the millimeters of water lost (including evaporation directly from the soil).

cryosphere
The portion of the climate system consisting of the world's ice masses and snow deposits, which includes the continental ice sheets, mountain glaciers, sea ice, surface snow cover, and lake and river ice. Changes in snow cover on the land surfaces are by and large seasonal and closely tied to the mechanics of atmospheric circulation. The glaciers and ice sheets are closely related to the global hydrologic cycle and to variations of sea level and change in volume and extent over periods ranging f…

decomposers
Heterotrophic organisms that break down dead protoplasm and use some of the products and release others for use by consumer organisms.

decomposition
The breakdown of matter by bacteria and fungi. It changes the chemical makeup and physical appearance of materials.

deep water
That part of the ocean below the main thermocline.

deforestation
The removal of forest stands by cutting and burning to provide land for agricultural purposes, residential or industrial building sites, roads, etc. or by harvesting the trees for building materials or fuel. Oxidation of organic matter releases CO2 to the atmosphere, and regional and global impacts may result.

dendrochronology
The dating of past events and variations in the environment and the climate by studying the annual growth rings of trees. The approximate age of a temperate forest tree can be determined by counting the annual growth rings in the lower part of the trunk. The width of these annual rings is indicative of the climatic conditions during the period of growth; wide annual rings signify favorable growing conditions, absence of diseases and pests, and favorable climatic conditions, while narrow rings in…

dendroclimatology
The use of tree growth rings as proxy climate indicators. Tree rings record responses to a wider range of climatic variables over a larger part of the Earth than any other type of annually dated proxy record.

desertification
The progressive destruction or degradation of vegetative cover especially in arid or semiarid regions bordering existing deserts. Overgrazing of rangelands, large-scale cutting of forests and woodlands, drought, and burning of extensive areas all serve to destroy or degrade the land cover. The climatic impacts of this destruction include increased albedo leading to decreased precipitation, which in turn leads to less vegetative cover; increased atmospheric dust loading could lead to decreased mo…

differentiation
The process by which single cells grow into particular forms of specialized tissue (e.g., root, stem, or leaf).

divergence
A horizontal flow of water, in different directions, from a common center or zone; it is often associated with upwelling. Also see convergence.

downwelling
The process of accumulation and sinking of warm surface waters along a coastline. A change of air flow of the atmosphere can result in the sinking or downwelling of warm surface water. The resulting reduced nutrient supply near the surface affects the ocean productivity and meteorological conditions of the coastal regions in the downwelling area.