- 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, ...
The nearly equal vertical and lateral dispersion of air pollutants from the centerline of a smoke plume, which occurs in statically neutral conditions (see static stability). As pollutants from a point source are blown downwind, the envelope of the smoke plume (as visible by eye or as measured by the percentage decrease of concentration from that at the centerline) takes the shape of a cone. Conversely, observation of a coning smoke plume can be used as an indicator that the ambient air there is statically neutral. Compare fanning, looping, fumigation.
Industry:Weather
The original unit of luminous intensity, defined as the luminous intensity of a candle of particular construction. The candle was eventually replaced by the international candle, the new candle in 1939, and finally the candela in 1948.
Industry:Weather
The name given to the foehn in western North America, especially on the plains to the lee or eastern side of the Rocky Mountains in the United States and Canada. On the eastern slopes of the Rocky Mountains the chinook generally blows from the west or southwest, although the direction may be modified by topography. Often the chinook begins to blow at the surface as an arctic front retreats to the east, producing dramatic temperature rises. Jumps of 10°–20°C can occur in 15 minutes, and at Havre, Montana, a jump from −12° to +5°C in 3 minutes was recorded. Occasionally the arctic front is nearly stationary and oscillates back and forth over an observing station, causing the temperature to fluctuate wildly as the station comes alternately under the influence of warm and cold air. As in the case of any foehn, chinook winds are often strong and gusty. They can be accompanied by mountain waves, and they can occur in the form of damaging downslope windstorms. The air in the chinook originates in midtroposphere above the ridgetops, and its warmth and dryness result from subsidence. When moisture is present, a variety of mountain-wave clouds and lee-wave clouds can form, such as the chinook arch of the Canadian Rocky Mountains west of Calgary, Alberta. The chinook brings relief from the cold of winter, but its most important effect is to melt or sublimate snow: A foot of snow may disappear in a few hours. As with the foehn, researchers have attempted to classify chinooks as downslope winds with warming and boras as those accompanied by cooling. Again, these schemes have produced limited success because of the many ambiguous or erroneously classified cases.
Industry:Weather
The minimum height above aerodrome level to which an approach to landing by an aircraft can safely be continued without visual reference to the ground.
Industry:Weather
The movement of the continents relative to each other. Continental drift is a consequence of plate tectonics. Continents generally move with respect to each other at the rate of a few centimeters per year.
Industry:Weather
The mean value assumed by a particular variate when the other variates considered are held fixed.
Industry:Weather
The mechanical forces exerted on soil water resulting from the curved interface between the air and water caused by the combined effect of surface tension and effective contact angle.
Industry:Weather
The migration of charged particles in a gaseous medium acted upon by an external electric field. See air–earth conduction current.
Industry:Weather
The many types of data - instrumental, historical (such as diaries or crop records), proxy (such as tree growth rings) - that constitute the major source of information for climate studies.
Industry:Weather
