- 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, ...
Weather variables, especially wind, temperature, relative humidity, and precipitation, that influence fire starts, fire behavior, or fire suppression.
Industry:Weather
Water in the larger, noncapillary pores of the soil that is free to drain because there is insufficient tension to hold the water against the force of gravity; it generally flows from the soil in the first 24 hours following its appearance in the soil profile. See also detention storage, field capacity, retention storage.
Industry:Weather
Water droplets suspended in the atmosphere in the vicinity the earth's surface that affect visibility. According to international definition, fog reduces visibility below 1 km (0. 62 miles). Fog differs from cloud only in that the base of fog is at the earth's surface while clouds are above the surface. When composed of ice crystals, it is termed ice fog. Visibility reduction in fog depends on concentration of cloud condensation nuclei and the resulting distribution of droplet sizes. Patchy fog may also occur, particularly where air of different temperature and moisture content is interacting, which sometimes make these definitions difficult to apply in practice. Fogs of all types originate when the temperature and dewpoint of the air become identical (or nearly so). This may occur through cooling of the air to a little beyond its dewpoint (producing advection fog, radiation fog or upslope fog), or by adding moisture and thereby elevating the dewpoint (producing steam fog or frontal fog). Fog seldom forms when the dewpoint spread is greater than 4°F. According to U. S. Weather observing practice, fog that hides less than 0. 6 of the sky is called ground fog. If fog is so shallow that it is not an obstruction to vision at a height of 6 ft above the surface, it is called simply shallow fog. In aviation weather observations fog is encoded F, and ground fog GF. Fog is easily distinguished from haze by its higher relative humidity (near 100%, having physiologically appreciable dampness) and gray color. Haze does not contain activated droplets larger than the critical size according to Köhler theory. Mist may be considered an intermediate between fog and haze; its particles are smaller (a few μm maximum) in size, it has lower relative humidity than fog, and does not obstruct visibility to the same extent. There is no distinct line, however, between any of these categories. Near industrial areas, fog is often mixed with smoke, and this combination has been known as smog. However, fog droplets are usually absent in photochemical smog, which only contains unactivated haze droplets.
Industry:Weather
Very generally, a piece of sea ice that is smaller than a medium-sized floe.
Industry:Weather
Very generally, air that is not modified by local influence to an appreciable extent. Compare free atmosphere.
Industry:Weather
Water dripping to the ground from trees or other objects that have collected the moisture from drifting fog. In some instances the dripping is as heavy as light rain, as sometimes occurs among the redwood trees along the coast of northern California. During the foggy but almost rainless summers of California, fog drip prevents an excessive aridity in the coastal forests. As much as 0. 05 in. Of water, equivalent to a moderate shower, has been collected from a California fog in a single night. From the aerodynamic principles underlying the theory of collection efficiency it is clear that the needlelike leaves of conifers are better adapted to the removal of droplets from drifting fog than are the broad leaves of most deciduous trees. This characteristic may have been crucial in the evolutionary development of the redwoods in the limited areas wherein they thrive. Man-made fog-water collectors have been constructed in western Chile that utilize fog drip to provide water to the local population.
Industry:Weather
Vertical raising of a portion of the earth's crust following the removal of an ice mass. Glacial rebound is the reaction to deglaciation.
Industry:Weather
Typically, a low area adjacent to a river or other body of water that is subject to flooding.
Industry:Weather
Use of radioactive isotopes present in a groundwater sample to estimate the length of time the groundwater has been in the subsurface. See also radioactive dating.
Industry:Weather
