- 行业: 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, ...
Pressure ice characterized by haphazardly arranged mounds or hillocks (“hummocks”). This has less definite form than rafted ice or tented ice, but in fact may develop from either of those as melting, sublimation, or drifting changes the sharper ice edges into more rounded shapes.
Industry:Weather
Popular term for aircraft and/or personnel engaged in tropical cyclone reconnaissance.
Industry:Weather
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.
Industry:Weather
Pertaining to winter. The corresponding adjectives for spring, summer, and fall are vernal, aestival, and autumnal.
Industry:Weather
Permeability at saturation. See effective permeability, relative permeability.
Industry:Weather
Pertaining to a quantity that has equal value in space at a particular time.
Industry:Weather
Pertaining to the process of mixing two radio signals of different frequencies to produce a third signal that is the difference of the two, that is, to produce beating between the two frequencies.
Industry:Weather
Periods of dry climate within the Pleistocene epoch during which lakes dried. Generally corresponding to glacials in regions with monsoonal climate and to interglacials in regions with Mediterranean climate.
Industry:Weather
Particles suspended in air, reducing visibility by scattering light; often a mixture of aerosols and photochemical smog. Many aerosols increase in size with increasing relative humidity due to deliquescence, drastically decreasing visibility. On Köhler curve plots of saturation relative humidity versus aerosol particle radius, equilibrium haze particles are to the left of the peak, while growing cloud droplets are to the right. Many haze formations are caused by the presence of an abundance of condensation nuclei which may grow in size, due to a variety of causes, and become mist, fog, or cloud. Distinction is sometimes drawn between dry haze and damp haze, largely on the basis of differences in optical effects produced by the smaller particles (dry haze) and larger particles (damp haze), which develop from slow condensation upon the hygroscopic haze particles. Dry haze particles, with diameters of the order of 0. 1 μm, are small enough to scatter shorter wavelengths of light preferentially though not according to the inverse fourth-power law of Rayleigh scattering. Such haze particles produce a bluish color when the haze is viewed against a dark background, for dispersion allows only the slightly bluish scattered light to reach the eye. The same type of haze, when viewed against a light background, appears as a yellowish veil, for here the principal effect is the removal of the bluer components from the light originating in the distant light-colored background. Haze may be distinguished by this same effect from mist, which yields only a gray obscuration, since the particle sizes are too large to yield appreciable differential scattering of various wavelengths. See smaze, arctic haze; compare particulates.
Industry:Weather
Oxygenated compounds that are organic derivatives of hydrogen peroxide. The simplest is methyl hydroperoxide, formula CH3OOH. These compounds are formed in the oxidation of hydrocarbons in relatively clean air, where oxides of nitrogen are not abundant. The presence of the alkyl group renders them much less soluble than hydrogen peroxide and therefore more susceptible to long-range transport in the atmosphere.
Industry:Weather
