- 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, ...
Particulate matter smaller than 2. 5 μm that is suspended in the air. See aerosol, airborne particulates, criteria pollutants.
Industry:Weather
Particulate matter smaller than 10 μm that is suspended in the air. See aerosol, airborne particulates, criteria pollutants.
Industry:Weather
Part of the storm rainfall that flows below the land surface for a certain distance before eventually reaching the surface channel after a fairly short time.
Industry:Weather
Part of an obsolete conceptual model of an air parcel ascent referring to that portion of the ascent during which the parcel undergoes pseudoadiabatic expansion at temperatures above freezing. Other portions of the ascent were described as the dry stage, snow stage, and hail stage.
Industry:Weather
Part of an obsolete conceptual model of air parcel ascent referring to conditions under which the condensation level is at a temperature below freezing and it is assumed that all condensed vapor immediately freezes. Other portions of the ascent were described as the dry stage, the rain stage, and the hail stage.
Industry:Weather
Parcels or strata of air having densities sufficiently different from that of their surroundings that they may be discerned by means of refraction anomalies in transmitted light. All of the natural scintillation phenomena in the atmosphere result from the presence of density schlieren developed by turbulent processes. The schlieren method is an experimental technique for optically detecting the presence of slight density, and hence temperature and/or pressure, variations in gases and liquids by virtue of refraction effects.
Industry:Weather
Orographic precipitation-enhancement mechanism, in which precipitation from an upper-level precipitating cloud (seeder) falls through a lower-level orographic stratus cloud (feeder) capping a hill or small mountain. Precipitation droplets or ice particles fall from the higher seeder cloud and collect cloud water as they pass through the lower feeder cloud by collision and coalescence or accretion, thus producing greater precipitation on the hill under the cap cloud than on the nearby flat land. The effectiveness of the process depends on sufficiently strong low-level moist flow to maintain the cloud water content in the orographic feeder cloud and the continuing availability of precipitation particles from the seeder cloud.
Industry:Weather
Originally defined in 1924 by Gilbert Walker as a low-latitude, planetary- scale “seesaw” in sea level pressure, with one pole in the eastern Pacific and the other in the western Pacific–Indian Ocean region. The pressure seesaw is associated with a global pattern of atmospheric anomalies in circulation, temperature, and precipitation. The primary timescale of the oscillation is interannual–multiyear, and it is now recognized to be primarily a response to basin-scale sea surface temperature variations in the equatorial Pacific arising from coupled ocean–atmosphere interactions, the opposite extremes of which are the El Niño and La Niña warm and cold events. See'' also'' ENSO.
Industry:Weather
Ordinary lightning, of a cloud-to-ground discharge, that appears to be entirely concentrated in a single, relatively straight lightning channel. Compare forked lightning, zigzag lightning.
Industry:Weather
Ordinary cloud-to-ground lightning that appears to be spread horizontally into a ribbon of parallel luminous streaks when a very strong wind is blowing at right angles to the observer's line of sight. Successive strokes of the lightning flash are then displaced by small angular amounts and may appear to the eye or camera as distinct paths. The same effect is readily created artificially by rapid transverse movement of a camera during film exposure.
Industry:Weather
