- 行业: Weather
- Number of terms: 60695
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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 measure of the difference between a forecast and the corresponding verification from analysis or observations.
Industry:Weather
A local approximation of the spherical earth as a plane normal to the zenithal component of the earth's rotation. The rotation rate f is assumed to be constant on the plane. This approximation is valid in describing atmospheric or oceanic motions with time scales smaller than or comparable to 1/f.
Industry:Weather
A local bowl-shaped region or depression in the surface in which, in suitable conditions, cold air accumulates during the night as the result of cold air drainage called katabatic wind. Such regions are subject to a greater incidence of frost, and to more severe frosts, than are the surrounding areas of nonconcave shape. See frost pocket.
Industry:Weather
A local dry wind in the northern plains of Java, resembling the foehn. It is caused by a wind crossing the mountains near the south coast and pushing between the volcanoes.
Industry:Weather
A magnetic field in a (zero resistivity) electrically conducting fluid (or plasma), so named because when the plasma moves, the magnetic lines of force may be said to move with it. The field lines are fixed within the plasma. Because a plasma is an electrical conductor, when it moves in a magnetic field an electric current results, which in turn produces a magnetic field that adds to the existing field. The net field (assuming negligible resistivity) is as if the existing field lines had moved with the plasma.
Industry:Weather
A lightning discharge in which the original leader process starts upward from some object on the ground; the opposite of the more common cloud-to-ground discharge. Ground-to-cloud discharges most frequently emanate from very tall structures that, being at the same potential as the earth, can exhibit the strong field intensities near their upper extremities necessary to initiate leaders.
Industry:Weather
A lightweight version of a propeller anemometer sometimes used instead of the more expensive sonic anemometer for the measurement of turbulent velocity fluctuations. The “traditional” Gill propeller anemometer is a three-axis arrangement, which is particularly suited for the measurement of the vertical wind. The so-called K-Gill propeller vane has two propellers, mounted at an angle of 90°, that are aligned with the mean wind by a vane. One particular type of sonic anemometer is sometimes referred to as “Gill sonic anemometer” in the literature of the early 1990s.
Industry:Weather
A line formed by the intersection of the surface of a sphere and a plane that passes through the center of the sphere.
Industry:Weather
A kinematic measure of the tendency of the flow in an air mass to increase the horizontal gradient of a conservative property θ, defined by the equation
where ∇H is the horizontal del operator. When θ is identified with the potential temperature, this function measures the frontogenesis in an air mass.
Industry:Weather
A hypothetical medium devoid of all matter (i.e., a perfect vacuum). No such medium exists except as an idealization. Even interstellar space is sparsely populated with atoms (mostly hydrogen), molecules, and particles.
Industry:Weather
