- 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, ...
1. To provide channels, such as open ditches or drain tile, so that excess water can be removed by surface or by internal flow. 2. To lose water from the soil by percolation. (Glossary of Terms in Soil Science, Agriculture Department of Canada, Publication 1459, revised 1976)
Industry:Weather
A device that measures wind speed by the drag force the wind produces on a solid sphere. Wind speed is proportional to the square root of the drag force. The sphere is often mounted on the end of a rod or pole, with strain gauges attached to the rod to measure the force indirectly.
Industry:Weather
An anemometer that measures the wind velocity by sensing the drag force on an object, commonly a cylinder or sphere, placed in the flow. The force is proportional to the square of the wind speed.
Industry:Weather
1. Generally, a small-scale current of air; usually applied to indoor air motion. 2. In aviation terminology (especially in connection with aircraft turbulence) a relatively small- scale current of air with marked vertical motion, that is, updraft or downdraft.
Industry:Weather
A downward motion of surface or subsurface water that removes excess mass brought into an area by convergent horizontal flow near the surface. See also upwelling.
Industry:Weather
The combination of downwelling shortwave and longwave radiation.
Industry:Weather
The downwelling component of longwave radiation. Its value at the surface is a measure of the greenhouse effect of the atmosphere. See also counterradiation.
Industry:Weather
A nocturnal, thermally forced along-valley wind produced as a result of nocturnal cooling of the valley air; a nocturnal component of the fair- weather mountain–valley wind systems encountered during periods of light synoptic or other larger-scale flow. Valley cooling is accomplished by the combined effects of draining cold air off the slopes by early-evening downslope (katabatic) winds, and upward motion with upward cold-air advection from the convergence of katabatic flows in the valley center. Air in the valley thus becomes cooler than air at the same level over the adjacent plain (see topographic amplification factor), producing higher pressure in the valley. The pressure gradient drives a downvalley wind that begins one to four hours after sunset, persists for the rest of the night until after sunrise, and often reaches 7–10 m s−1 or more above the surface. The downvalley wind tends to fill the valley, that is, its depth is approximately the depth of the valley, and where mountains end and a valley empties onto the plains, the downvalley wind can become a cold-air valley outflow jet flowing out of the mouth of the valley. See drainage wind, along-valley wind systems.
Industry:Weather
