- Industry: Weather
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The American Meteorological Society promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications. Founded in 1919, AMS has a membership of more than 14,000 professionals, ...
The extension of a relationship between two or more variables beyond the range covered by knowledge, or the calculation of a value outside that range. In synoptic meteorology, extrapolation commonly refers to the forecasting of the position of a weather-pattern feature based solely upon recent past motion of that feature. Compare interpolation.
Industry:Weather
The area that, when multiplied by the irradiance of electromagnetic waves incident on an object, gives the total radiant flux scattered and absorbed by the object. Customary usage in radar describes the attenuation cross section as the area that, when multiplied by the power density of incident plane-wave radiation, gives the power removed from the beam by absorption and scattering. For a propagation medium consisting of a dispersion of scattering and absorbing objects, the volume extinction coefficient (m2m−3 or m−1) at a given location in the medium is the sum of the extinction cross sections of all the objects in a unit volume centered at the location. Compare scattering cross section, absorption cross section.
Industry:Weather
The physical process by which a liquid or solid is transformed to the gaseous state; the opposite of condensation. Evaporation is usually restricted in use to the change of water from liquid to gas, while sublimation is used for the change from solid to gas. According to the kinetic theory of gases, evaporation occurs when liquid molecules escape into the vapor phase as a result of the chance acquisition of above-average, outward-directed, translational velocities at a time when they happen to lie within about one mean free path below the effective liquid surface. It is conventionally stated that evaporation into a gas ceases when the gas reaches saturation. In reality, net evaporation does cease, but only because the numbers of molecules escaping from and returning to the liquid are equal, that is, evaporation is counteracted by condensation. Because the molecules that escape the condensed phase have above-average energies, those left behind have below-average energies, which is manifested by a decrease in temperature of the condensed phase (unless compensated for by energy transfer from the surroundings). See also evapotranspiration.
Industry:Weather
A theoretical boundary between a region in the fluid where waves of some frequency are propagating and a region in the fluid where waves of the same frequency do not propagate (where they are evanescent). This is also called a critical level but is distinct from the critical level where the background flow has the same speed as the phase speed of the waves.
Industry:Weather
The removal of radiant energy from an incident beam by the processes of absorption and/or scattering.
Industry:Weather
The physical process by which a liquid or solid is transformed to the gaseous state; the opposite of condensation. Evaporation is usually restricted in use to the change of water from liquid to gas, while sublimation is used for the change from solid to gas. According to the kinetic theory of gases, evaporation occurs when liquid molecules escape into the vapor phase as a result of the chance acquisition of above-average, outward-directed, translational velocities at a time when they happen to lie within about one mean free path below the effective liquid surface. It is conventionally stated that evaporation into a gas ceases when the gas reaches saturation. In reality, net evaporation does cease, but only because the numbers of molecules escaping from and returning to the liquid are equal, that is, evaporation is counteracted by condensation. Because the molecules that escape the condensed phase have above-average energies, those left behind have below-average energies, which is manifested by a decrease in temperature of the condensed phase (unless compensated for by energy transfer from the surroundings). See also evapotranspiration.
Industry:Weather
A wave in fluid motion having its maximum amplitude at an external boundary such as a free surface. Any surface wave on the free surface of a homogeneous incompressible fluid is an external wave. Compare internal wave.
Industry:Weather
Any property of a parcel or system that is a function of the mass of the system, for example, kinetic or internal energy. See intensive quantity.
Industry:Weather
That part of the hydrologic cycle pertaining to water that evaporates from the sea surface and subsequently falls as precipitation on the continent.
Industry:Weather
Boundary conditions (such as surface drag against the surface) and body forcings (such as heating caused by infrared radiation divergence within the air) that are imposed on the atmosphere from outside the domain of interest. The exact definition depends on the scale context of the problem. For example, boundary layer meteorologists might consider geostrophic wind to be imposed as an external forcing at a single weather station, while general circulation dynamicists might calculate geostrophic wind as an internal variable based on the global differential heating imposed on the earth as an external forcing by the sun.
Industry:Weather
