- 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 ratio of the amplitude of the reflected electric field to the amplitude of the field incident at the optically smooth planar interface between two optically homogeneous media. The incident and reflected fields are plane harmonic and the interface is large in lateral extent compared with the wavelength of the illumination. May also be used for the ratio of reflected to incident irradiances, that is, the ratio of the normal (to the interface) component of the reflected Poynting vector to that of the incident normal. A better term for this quantity is reflectivity. The reflection coefficient (and hence reflectivity) depends on the angle of incidence of the illumination, its wavelength (by way of the wavelength-dependence of the relative refractive index of the two media), and its state of polarization. These coefficients taken together are sometimes called the “Fresnel formulae” or “Fresnel relations. ” Reflection coefficient may mean the ratio of any reflected to incident irradiance (reflectivity). See'' also'' transmission coefficient.
Industry:Weather
Precipitation in the form of very small, white opaque particles of ice; the solid equivalent of drizzle. They resemble snow pellets in external appearance, but are more flattened and elongated, and generally have diameters of less than 1 mm; they neither shatter nor bounce when they hit a hard surface. Descriptions of the physical structure of snow grains vary widely and include very fine, simple ice crystals; tiny, complex snow crystals; small, compact bundles of rime; and particles with a rime core and a fine glaze coating. It is agreed that snow grains usually fall in very small quantities, mostly from stratus clouds or from fog, and never in the form of a shower.
Industry:Weather
A form of the primitive equations in which an approximation to the actual winds is selectively used in the momentum and thermodynamic equations. Specifically, horizontal winds are replaced by their geostrophic values in the horizontal acceleration terms of the momentum equations, and horizontal advection in the thermodynamic equation is approximated by geostrophic advection. In addition, the quasigeostrophic approximation neglects vertical advection of momentum and replaces the four-dimensional static stability parameter with a basic-state static stability, which is a function of the vertical coordinate only. The quasigeostrophic approximation is used in the analysis of extratropical synoptic-scale systems, in which winds can be closely approximated by their geostrophic values. This approximation is not accurate in situations in which the ageostrophic wind plays an important advective role, for example, around fronts.
Industry:Weather
In general, the climate of the ice cap regions of the world; thus, it requires temperatures sufficiently cold so that the annual accumulation of snow and ice is never exceeded by ablation. The perpetual frost climate is one of the polar climates in W. Köppen's climatic classification and is characterized by a warmest-month mean temperature of less than 0°C (32°F). It is designated by letter code ''EF'' and is equivalent to the frost climate of C. W. Thornthwaite's classifications and to Nordenskjöld's (1928) high arctic climate.
Industry:Weather
A climatic zone located in the polar latitudes marked by conditions too harsh to support vegetation. See Frigid zone.
Industry:Weather
A measure of the degree to which the weather or climate of a region is favorable to the process of evaporation. It is usually considered to be the rate of evaporation, under existing atmospheric conditions, from a surface of water that is chemically pure and has the temperature of the lowest layer of the atmosphere. See Bowen ratio, relative evaporation.
Industry:Weather
In general, the difference between any quantity and an approximation to it; in particular, the difference (''y'' − ''Y'') between any random variable ''y'' and its regression function ''Y''. See regression.
Industry:Weather
In hydrology, a procedure used to derive a downstream hydrograph from an upstream hydrograph (and/or tributary hydrographs) and considerations of local inflow by solving the storage equation.
Industry:Weather
Permanently frozen ground (permafrost) that, under present climatic conditions, will not refreeze if thawed; opposed to active permafrost.
Industry:Weather
The ratio of the amplitude of the reflected electric field to the amplitude of the field incident at the optically smooth planar interface between two optically homogeneous media. The incident and reflected fields are plane harmonic and the interface is large in lateral extent compared with the wavelength of the illumination. May also be used for the ratio of reflected to incident irradiances, that is, the ratio of the normal (to the interface) component of the reflected Poynting vector to that of the incident normal. A better term for this quantity is reflectivity. The reflection coefficient (and hence reflectivity) depends on the angle of incidence of the illumination, its wavelength (by way of the wavelength-dependence of the relative refractive index of the two media), and its state of polarization. These coefficients taken together are sometimes called the “Fresnel formulae” or “Fresnel relations. ” Reflection coefficient may mean the ratio of any reflected to incident irradiance (reflectivity). See'' also'' transmission coefficient.
Industry:Weather
