- 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, ...
In general, any effort to alter artificially the natural phenomena of the atmosphere. The term usually refers to cloud seeding activities, but can also include constructing windbreaks, dissipating fog by the forceful addition of heat or water spray, or preventing frost formation on crops by cloud spray, heating, or mixing processes. Inadvertent weather modification refers to accidental weather effects resulting from the release of greenhouse gases, aerosols, and dust, or changes in albedo or surface properties of the earth associated with urban, industrial, or agricultural activity.
Industry:Weather
A device for measuring sea surface waves. It consists of a weighted pole below which a disk is suspended at sufficient depth for the wave motion associated with deep-water waves to be negligible. The pole will then remain nearly as if anchored to the bottom, and wave height and period can be ascertained by observing or recording the length of the pole that extends above the surface. See wave recorder; Compare tide gauge.
Industry:Weather
A device for measuring sea surface waves. It consists of a weighted pole below which a disk is suspended at sufficient depth for the wave motion associated with deep-water waves to be negligible. The pole will then remain nearly as if anchored to the bottom, and wave height and period can be ascertained by observing or recording the length of the pole that extends above the surface. See wave recorder; Compare tide gauge.
Industry:Weather
A cyclone that forms and moves along a front. The circulation about the cyclone center tends to produce a wavelike deformation of the front. The wave cyclone is the most frequent form of extratropical cyclone (or low). It was the purpose of the wave theory of cyclones to explain its life cycle.
Industry:Weather
A cyclone that forms and moves along a front. The circulation about the cyclone center tends to produce a wavelike deformation of the front. The wave cyclone is the most frequent form of extratropical cyclone (or low). It was the purpose of the wave theory of cyclones to explain its life cycle.
Industry:Weather
A basic sampling problem that arises when the unambiguous velocity sampling interval is less than the full range of naturally occurring velocities, causing the erroneous appearance of higher velocities within the sampling interval. This phenomenon occurs in Doppler velocity measurements when the maximum unambiguous velocity interval (±''V''<sub>max</sub>) is less than the full range of velocities being measured. Any true velocity, ''V'', appears within the interval from −''V''<sub>max</sub> to +''V''<sub>max</sub>, with the value ''V''′, which is related to the true velocity by ''V'' = ''V''′ ± 2''nV''<sub>max</sub> where ''n'' is an integer. Therefore a given measured velocity ''V''′ may be caused by many values of the true velocity ''V''. For example, suppose ''V''<sub>max</sub> = 25 m s<sup>−1</sup> and the measured velocity ''V''′ = −15 m s<sup>−1</sup>. Then the values of true velocity that could account for this measurement are the following: −15 m s<sup>−1</sup> (for ''n'' = 0); +35 or −65 m s<sup>−1</sup> (for ''n'' = 1); +85 or −115 m s<sup>−1</sup> (for ''n'' = 2); etc. In some instances the erroneous velocities can be recognized and ambiguities resolved by additional considerations, such as the requirement of spatial continuity of the velocity field. See Also aliasing, Nyquist frequency.
Industry:Weather
A region, or “pool,” of relatively warm air surrounded by colder air; the opposite of a cold pool. The common application of this term is to warm air of appreciable vertical extent isolated in high latitudes when a cut-off high is formed. Warm pools can be identified as thickness maxima on thickness charts.
Industry:Weather
An aircraft flight under conditions that allow navigation by visual reference to the earth's surface at a safe altitude and with sufficient horizontal visibility. Such a flight operates under visual flight rules. See Also VFR on top, VFR between layers.
Industry:Weather
The difference between consecutive daily mean values of the horizontal component of the geomagnetic field. Each value is derived from a 48-hour interval covering two GMT days and is assigned to the second day of the pair. The monthly U index, the mean of the daily values, is the most frequently used. See u index.
Industry:Weather
A measurement of the vertical profile of the thermodynamic and kinematic state of the atmosphere. A radiosonde makes an in situ point measurement of the atmosphere that it passes through. In contrast, a radar or lidar profiler makes a remotely sensed volumetric measurement of the atmosphere above the profiler location. See Also radiosonde observation, rawinsonde, rocketsonde, sounding.
Industry:Weather
