- 行业: Weather
- Number of terms: 60695
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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 lowest region of the ionosphere. The term is used somewhat loosely to describe the ionization, beginning about 70 km and merging with the E-region, that does not usually produce an echo on normal ionosonde recordings. The main effect of the D-region on radio waves is one of absorption, thus inhibiting long- distance propagation of HF and VHF radio waves in daytime, when D-region ionization is most intense. At low and middle latitudes, the D-region is produced mainly by the action of solar radiation on nitric oxide (NO). At high magnetic latitudes energetic particles of solar or auroral origin may be the principal source, in which case radio waves can be strongly absorbed at all times of day. The term D-layer is used occasionally by analogy with the higher E- and F-layers, which produce sharply defined echoes on ionosonde recordings.
Industry:Weather
A plot of the decline of water table or piezometric level versus distance from a pumping well, or versus time at a given distance from a pumping well, resulting from the continuous pumping from a well discharging at a known rate.
Industry:Weather
The decline in the water table level or piezometric level versus distance from a pumping well, or versus time at a given distance from a pumping well, resulting from the continuous pumping from a well discharging at a known rate.
Industry:Weather
Cold-air-runoff winds that are produced when air in contact with terrain surfaces is cooled and flows downslope and/or downvalley. This generic term is often used to indicate aggregate downslope (katabatic) and downvalley flows, when it is difficult to distinguish between the two. This happens frequently in basins, at the upper end of valleys, in complicated topography where the downslope and downvalley directions are not perpendicular, and in simple valleys when the weaker and shallower downslope flows are masked or overwhelmed by the stronger downvalley flow. Over even gently sloping topography, drainage winds also refer to gravity winds that drain cold air into frost hollows, river valleys, and other lower-lying terrain. See downslope wind.
Industry:Weather
A well designed for the purpose of removing the gravity-drained water from a saturated, porous medium. It is used in dams to reduce the amount of seepage entering the downstream face of the dam.
Industry:Weather
The line following the ridges or summits that form the exterior boundary of a watershed, river basin, or catchment. A drainage divide separates the area tributary to a particular stream from the area's tributaries to adjacent streams.
Industry:Weather
One of the means of numerically characterizing a stream for study and comparative purposes, computed by dividing the length of the stream channel by its drainage area; usually expressed in miles per square mile.
Industry:Weather
The total area upstream of a specific point, drained by the stream and its tributaries.
Industry:Weather
Any portion of the earth's surface within a physical boundary defined by topographic slopes that diverts all runoff to the same drainage outlet.
Industry:Weather
