- المجال: 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, ...
In reference to wells, groundwater that trickles or pours through cracks or perforations down the casing or uncased borehole above the water level in the well.
Industry:Weather
In radar, the four-dimensional volume given by the product of the coherence time and the pulse volume, within which the target signal is partially correlated. To estimate the power of the target signal requires averaging over several independent samples, which means averaging signals from a measurement cell that is large compared with the coherence element.
Industry:Weather
In radar, scattering produced when the incident wave encounters a point target that is either fixed or moving with a constant radial velocity, or a distributed target with individual scattering elements fixed or slowly moving relative to one another. Such targets give coherent echoes.
Industry:Weather
In radar, a representation of the time-varying amplitude and phase of the received signal as the real and imaginary parts of a time-varying complex number. These parts are called the in-phase and quadrature components and are measured by coherent detection of the received signal. The in-phase signal may be obtained by demodulating the received signal with a local oscillator having the same phase and frequency as the transmitted signal, while the quadrature signal may be obtained by demodulating the received signal with the local oscillator signal advanced or retarded in phase by 90°. See I and Q channels.
Industry:Weather
In radar, a matrix comprising the autocovariances and cross covariances of a set of signal amplitudes. As applied to polarimetric radar signals, the diagonal terms are the respective autocovariances of the received signals of orthogonal polarization, that is, the power in the two orthogonal channels, and the off-diagonal terms are the cross covariances.
Industry:Weather
In radar usage, a local maximum in radar reflectivity that undergoes a life cycle of growth and decay. The rising portion of the reflectivity maximum is indicative of updraft, and the later descending portion is indicative of a precipitation downdraft. Cells in ordinary convective storms last from 20 to 30 min, but often form longer-lasting multicell convective storms. Cells in supercell storms are more steady and last considerably longer. See also thunderstorm cell.
Industry:Weather
In oceanography, an instrument that measures current simultaneously over a range of depths. For example, an acoustic Doppler current profiler measures the current by the Doppler effect on backscattered sound waves over a range of depths.
Industry:Weather
In northeast Brazil, light showers occurring in October. The rainy season in Brazil normally begins in December and lasts until April or May; then follows a dry season until the rains at the end of the year. In October of most years, however, there will be local showers known as chuvas de cajú (cashew rains), so-called because they occur at the time of blossom of the cashew tree.
Industry:Weather
In northern China, rain during the early spring that helps the winter wheat. There is a Chinese proverb: Chunyuh is as valuable as oil.
Industry:Weather
