- 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 common form of cloud-to-ground discharge always visually present to a greater or lesser degree that exhibits downward-directed branches from the main lightning channel. In general, of the many branches of the stepped leader, only one is connected to the ground, defining the primary, bright return stroke path; the other incomplete channels decay after the ascent of the first return stroke. Compare streak lightning, zigzag lightning.
Industry:Weather
The common unit of depth in the ocean, equal to six feet. It is also sometimes used in expressing horizontal distances, in which case 100 fathoms is equivalent to one cable or very nearly to one-tenth of a nautical mile.
Industry:Weather
The coming together (usually horizontally) of air due to drag against the surface being different at different locations. A classic example is the wind blowing toward shore from over the ocean. The ocean is relatively smooth with little frictional drag, while the land, with trees and buildings, is rougher and has more drag. When the wind from the ocean reaches land, it will slow down due to the increased drag. Thus, air will be flowing toward the shore from the ocean faster than it will leave the shore over land, causing horizontal convergence. Mass continuity requires updrafts in these regions, thereby leading to enhanced cloudiness and possibly precipitation. See aerodynamic roughness length.
Industry:Weather
The combined effect, on an aircraft structure, of a gust and the pilot's effort to counteract the gust. American commercial airplanes are designed for a gust load equivalent to that which would be produced by a gust having an effective gust velocity of 30 ft s−1 at an airspeed equal to the design cruising speed of the aircraft.
Industry:Weather
The coldest temperature province in C. W. Thornthwaite's 1931 climatic classification. It is the climate of the ice cap regions of the earth, that is, those regions perennially covered with snow and ice. It is equivalent to the more commonly used term perpetual frost climate, to the colder of Köppen's (1918) polar climates, and to Nordenskjöld's (1928) high arctic climate.
Industry:Weather
The branch of physical chemistry that deals with the determination of the rates and mechanisms of chemical reactions occurring in the gas phase.
Industry:Weather
The coldest (below −1. 1°C) and densest component of the water masses that mix to produce the Arctic Bottom Water.
Industry:Weather
The boundary between groundwater basins; defined by a line connecting the high points on the water table or other potentiometric surface. Groundwater flows away from a groundwater divide.
Industry:Weather
The boundary of the area of snow on a glacier surviving one year's ablation, thus becoming firn. In the absence of superimposed ice, this limit is equivalent to the equilibrium line. See climate snow line.
Industry:Weather
The application of ray tracing to explain scattering and refractive effects by particles that are very large compared with the wavelength of the radiation. Geometric optics provides useful explanations for atmospheric features such as rainbows, halos, and many other ice crystal optical displays.
Industry:Weather
