- 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 type of synoptic chart showing the thickness of a certain physically defined layer in the atmosphere. Currently it almost always refers to an isobaric thickness chart, that is, a chart of vertical distance between two constant-pressure surfaces and is often proportional to the temperature of that layer. This chart consists of a pattern of thickness lines either drawn directly to data plotted on the chart or, more commonly, drawn by the single graphical process of differential analysis. See isentropic thickness chart, vertical differential chart.
Industry:Weather
A type of snow crust; a patch of hard-packed snow that is packed as it is deposited in favored spots by the wind (in contrast to wind crust, which is packed after deposition). Wind slabs can be quite rigid, but they adhere poorly to the underlying snow and hence may be readily dislodged, causing an avalanche.
Industry:Weather
A type of snow crust formed by the packing action of wind on previously deposited snow. Wind crust may break locally, but, unlike wind slab, does not constitute an avalanche hazard.
Industry:Weather
A type of precipitation echo observed in connection with large, strong tornadoes located at relatively close ranges from a radar. It appears on PPI displays in the form of a doughnut-shaped echo at the end of a hook echo in a supercell thunderstorm. A quasi-vertical tube having minimum radar reflectivity in the center may be observed on an RHI display or on a vertical sequence of PPI displays.
Industry:Weather
A type of forest that exists in cool but generally frost-free regions of heavy annual precipitation. It consists mainly of mixed deciduous trees, usually with one dominant species. With the onset of winter the forest becomes dormant and remains so until spring, when it resumes active growth. Temperate rain forests are found principally near the west coasts of southern South America and northern North America, in New Zealand, and in northern Japan. Compare tropical rain forest.
Industry:Weather
A type of fog formed when air flows upward over rising terrain and is, consequently, adiabatically cooled to or below its dewpoint.
Industry:Weather
A radar analysis technique that makes use of radial velocity measurements by three or more Doppler radars to deduce the three-dimensional velocity vector of radar echoes. Such observations allow more accurate determination of the three-dimensional velocity than dual-Doppler analysis, which requires additional assumptions about boundary conditions to estimate the vertical velocity component.
Industry:Weather
A type of conductor used to carry VHF or microwave energy from one point to another. Most waveguides are hollow (rectangular or circular) and carefully dimensioned according to the frequency and energy to be conducted. For low-power, short-distance applications a coaxial cable may be used as waveguide. Its primary use in radar is in providing a path for the radio energy between the antenna and the transmitting and receiving systems. Properly shaped open waveguides can themselves be used as radiators (horn antennas) or as feeds at the foci of reflecting antennas.
Industry:Weather
A type of air mass with characteristics developed over low latitudes. Maritime tropical air (''mT''), the principal type, is produced over the tropical and subtropical seas. It is very warm and humid and is frequently carried poleward on the western flanks of the subtropical highs. Continental tropical air (''cT'') is produced over subtropical arid regions and is hot and very dry. See airmass classification, trade air; Compare polar air.
Industry:Weather
A tube designed to measure the rate of flow of fluids. It consists of a tube having a constriction or throat at its midsection. The difference between the pressure measured at the inlet and at the throat is a function of the fluid velocity. The instrument is frequently used in wind-tunnel work and as a speed indicator for aircraft. Compare Pitot tube.
Industry:Weather
