- 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, ...
Vision mediated by rods alone at very low levels of luminance. Rods do not allow color vision. See dark adaptation.
Industry:Weather
Volume of water added to an aquifer per unit area and per unit time.
Industry:Weather
Volume per unit mass of a substance, and hence the reciprocal of density; commonly symbolized by ''v'' or α.
Industry:Weather
Washout of radioactive aerosol particles following release into the atmosphere from 1950s weapon tests above ground or from nuclear reactor leaks, as at Chernobyl.
Industry:Weather
Water held in a reservoir for short periods to regulate natural flow, usually for hydroelectric power.
Industry:Weather
Water retained in the capillary pores (micropores) of the soil where there is sufficient tension to retain the moisture against the force of gravity, so that it is not free to drain, and is in large part available to plants. See'' also'' detention storage, field capacity, gravitational water.
Industry:Weather
Water that, having been diverted from a water body, usually for irrigation, is not consumed in the process and flows back to the original or some other water body.
Industry:Weather
Water without significant hardness, that is, low (< 60 mg/l) in concentration of magnesium or calcium salts.
Industry:Weather
Weak luminous emissions that appear directly above an active thunderstorm and are coincident with cloud-to-ground or intracloud lightning flashes. Their spatial structures range from small single or multiple vertically elongated spots, to spots with faint extrusions above and below, to bright groupings that extend from the cloud tops to altitudes up to about 95 km. Sprites are predominantly red. The brightest region lies in the altitude range 65–75 km, above which there is often a faint red glow or wispy structure that extends to about 90 km. Below the bright red region, blue tendril-like filamentary structures often extend downward to as low as 40 km. High-speed photometer measurements show that the duration of sprites is only a few milliseconds. Current evidence strongly suggests that sprites preferentially occur in decaying portions of thunderstorms and are correlated with large positive cloud-to-ground flashes. The optical intensity of sprite clusters, estimated by comparison with tabulated stellar intensities, is comparable to a moderately bright auroral arc. The optical energy is roughly 10– 50 kJ per event, with a corresponding optical power of 5–25 MW. Assuming that optical energy constitutes 10<sup>−3</sup> of the total for the event, the energy and power are on the order of 10–100 MJ and 5–50 GW, respectively. Early research reports for these events referred to them by a variety of names, including upward lightning, upward discharges, cloud-to-stratosphere discharges, and cloud-to-ionosphere discharges. Now they are simply referred to as sprites, a whimsical term that evokes a sense of their fleeting nature, while at the same time remaining nonjudgmental about physical processes that have yet to be determined. Compare blue jets.
Industry:Weather
