- 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, ...
A theory of cyclone development in which upper-level divergence in the atmosphere, through the principle of mass continuity, induces low-level convergence of air that develops cyclonic circulation through the process of geostrophic adjustment.
Industry:Weather
Transfer of water from one watercourse to another, such watercourses being either natural or man-made.
Industry:Weather
Any horizontal line along which horizontal divergence of the airflow is occurring.
Industry:Weather
The statement that the volume integral of the divergence of a vector, such as the velocity V, over a volume V is equal to the surface integral of the normal component of V over the surface s of the volume (often called the “export” through the closed surface), provided that V and its derivatives are continuous and single-valued throughout V and s. This may be written
where n is a unit vector normal to the element of surface ds, and the symbol ∮ ∮S indicates that the integration is to be carried out over a closed surface. This theorem is sometimes called Green's theorem in the plane for the case of two-dimensional flow, and Green's theorem in space for the three-dimensional case described above. The divergence theorem is used extensively in manipulating the meteorological equations of motion.
Industry:Weather
A pattern in a Doppler velocity field representing horizontal divergence (or convergence) associated with atmospheric phenomena. In a storm-relative reference frame, the idealized signature associated with flow diverging from a point source (or converging toward a sink) is symmetric about a line perpendicular to the radar viewing direction with marked radial shear across the core region between peak Doppler velocity values of opposite sign. The signature associated with a divergence line (or convergence line) depends on the Doppler radar viewing direction. When the radar viewing direction is perpendicular to the line, there is a band of radial shear across the line that corresponds to the full measure of divergence (convergence). When the viewing direction is parallel to the line, none of the divergence is sensed by the radar. At angles in between, a fraction of the divergence is sensed.
Industry:Weather
A function F(x) yielding the probability that a stated random variable will assume some value less than or equal to any arbitrary number x. By definition, the distribution function is identically zero for all values of x below the least admissible value of the random variable, and identically unity for all values of x equal to or greater than the greatest admissible value of the random variable. Moreover, F(x2) ≥ F(x1) whenever x2 > x1. Sometimes, for the sake of clarity, the distribution function is called the cumulative distribution function. Compare probability density function.
Industry:Weather
Any horizontal line along which horizontal divergence of the airflow is occurring.
Industry:Weather
An equation for the rate of change of horizontal divergence on a parcel (in analogy to the vorticity equation). For frictionless flow this equation is
where ∇p u is the horizontal divergence, J(u, v) is the Jacobian, ω is the material rate of change of pressure, β is the Rossby parameter, ζ is the vertical vorticity, and φ is the geopotential. All horizontal differentiations are carried out in a constant-pressure surface. The divergence equation is derived by taking the divergence of the vector equation of motion. When the two terms in the divergence are neglected, this equation becomes the balance equation.
Industry:Weather
The vertical movement in the ocean of zooplankton, which feed near the surface at night on phytoplankton in the euphotic zone and sink downward several hundred meters during daytime, presumably to escape larger predators.
Industry:Weather
