- 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, ...
1. A discontinuity in a function or a derivative of a function such that it assumes different values at a point when the point is approached from different directions. 2. See pressure jump.
Industry:Weather
1. A damp unpleasant wind that blows from the south in Madras (India). 2. A wind from the northeast at night in Sri Lanka.
Industry:Weather
1. 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. The parent cloud does not contain a preexisting midlevel mesocyclone. The landspout was so named because it looks like a weak, Florida Keys waterspout over land. See nonsupercell tornado.
Industry:Weather
1. With regard to atmospheric circulation, a wave in the major belt of westerlies that is characterized by large length and significant amplitude. The wave length is typically longer than that of the rapidly moving individual cyclonic and anticyclonic disturbances of the lower troposphere. The angular wavenumber of long waves is generally taken to be from 1 to 5. Compare short wave; see Rossby wave. 2. (Also called shallow water wave. ) A wave with a relatively long wave length and period. For ocean waves, this is typically a wave of period greater than about 10 s and wave length greater than about 150 m.
Industry:Weather
The slowly propagating electrical breakdown process in a cloud carrying net charge; it can initiate a K process. See K changes.
Industry:Weather
The slowly propagating electrical breakdown process in a cloud carrying net charge; it can initiate a K process. See K changes.
Industry:Weather
An inert element, fourth member of the noble gas family, atomic number 36, atomic weight 83. 7; an element found in the atmosphere to the extent of only 0. 000114% by volume.
Industry:Weather
(Symbol β2 or α4. ) A descriptive measure of a random variable in terms of the flatness of its probability distribution. It is defined as follows:
where μ4 is the fourth (statistical) moment about the mean and σ2 the variance. For the normal distribution, β2 = 3; and it is commonly (though not invariably) found that curves for which β2 > 3 are more sharply peaked than the normal, while those for which β2 < 3 are flatter than the normal. In particular, the rectangular distribution f(x) = 1 (0 < x < 1) has β2 = 1. 8. The terms leptokurtic, mesokurtic, and platykurtic refer to curves for which the values of β2 are, respectively, greater than 3, equal to 3, and less than 3. Excess is a relative expression for kurtosis, and the coefficient of excess γ2 is defined as β2 − 3.
Industry:Weather
1. The time required for the earth to rotate once with respect to the moon, that is, the time between two successive upper transits of the moon. The mean lunar day is approximately 1. 035 times as great as the mean solar day, or 24 hours 50 minutes. 2. In astronomy, the time required for the moon to revolve once, relative to a fixed star, about its own axis.
Industry:Weather
