- 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, ...
An aviation weather observation taken primarily for aviation radio broadcast purposes. It is usually abbreviated to include just those elements of a record observation that have an important effect on aircraft operations, such as ceiling, visibility, state of sky, atmospheric phenomena, wind speed and direction, altimeter setting, and pertinent remarks.
Industry:Weather
An automatic, active, remote-sensing instrument for detecting the presence of clouds overhead and measuring the height of their bases. For optically thin clouds, such as most cirrus, more than one layer may be detected, but when optically thick clouds, such as liquid water stratus, are present, the light beam is unlikely to penetrate much beyond the base of the lowest liquid layer. Laser ceilometers use intense pulses of light in a very narrowly collimated, vertically directed beam, and have collocated transmitter and receiver systems. The cloud base heights may be displayed in a variety of time-height section images or backscatter intensity profile plots. Some older ceilometers use separated transmitter and receiver units. The instruments are designed to work during the day or night.
Industry:Weather
An atmospheric cyclonic circulation, a closed circulation. A cyclone's direction of rotation (counterclockwise in the Northern Hemisphere) is opposite to that of an anticyclone. While modern meteorology restricts the use of the term cyclone to the so-called cyclonic-scale circulations, it is popularly still applied to the more or less violent, small- scale circulations such as tornadoes, waterspouts, dust devils, etc. (which may in fact exhibit anticyclonic rotation), and even, very loosely, to any strong wind. The first use of this term was in the very general sense as the generic term for all circular or highly curved wind systems. Because cyclonic circulation and relative low atmospheric pressure usually coexist, in common practice the terms cyclone and low are used interchangeably. Also, because cyclones are nearly always accompanied by inclement (often destructive) weather, they are frequently referred to simply as storms. See tropical cyclone, extratropical cyclone; compare trough.
Industry:Weather
An atmometer consisting of a porous porcelain container connected to a calibrated reservoir filled with distilled water. Evaporation is determined by the depletion of water in the reservoir.
Industry:Weather
An atlas containing maps and tables of climatic data usually including distributions of highest and lowest temperatures by month, temperature means by month, diurnal ranges of temperature by month, frequency of wind direction and speed for several class values, monthly average and extreme precipitation, number of days per month with temperatures above and/or below specified values, etc. , at fixed locations over land, or within geographic areas at sea. Marine climatic atlases often include frequencies of sea level pressure values, wave heights, gale-force winds, and other phenomena of significance to mariners.
Industry:Weather
An array of clouds, not necessarily all of the same type, with bases at approximately the same level. It may be either continuous or composed of detached elements.
Industry:Weather
An area of the sea covered by ice of various origins consolidated, by wind and currents, into a solid mass.
Industry:Weather
An area in the atmosphere that transports cold air from one place to another. It often refers to the low-level airflow within the relatively cold air ahead of a developing cyclone.
Industry:Weather
An area of low atmospheric pressure within which more than one low pressure center is found.
Industry:Weather
An arc parallel to the horizon and found at least 46° below the sun (or moon). It is produced by the refraction of light through the 90° prisms of ice crystals, having entered through the vertical sides and passing out through the horizontal bases. Normally, the crystals are large, oriented, hexagonal plates. The circumhorizontal arc is the low sky counterpart of circumzenithal arc. The circumhorizontal arc is low in the sky when the sun is high (above 58° elevation); the circumzenithal arc is high in the sky when the sun is low (below 32° elevation). The most colorful circumhorizontal arcs occur when the refraction is close to the minimum angle of deviation, and this corresponds to a solar elevation angle of about 68°. In the midlatitudes, the sun only climbs to that elevation for a few hours mid day around the summer solstice.
Industry:Weather
