- 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 production of small wavelength mountain waves near a mountaintop under conditions of very strong static stability. When the air is very stable and wind speeds are slow, the natural wavelength of air is often much shorter than the width of the mountain, as indicated by a very small Froude number. For this situation, the buoyant restoring force in the air is so strong that the air resists vertical displacement to get over the mountaintop, and instead most of the air flows around the sides of the mountain. The shallow layer of air near the mountaintop that is able to be displaced upward over the mountain will continue in vertical oscillation as it blows downstream, or separates, from the mountain. Compare lenticular cloud, downslope windstorm.
Industry:Weather
The production of weather and climate idiosyncrasies at a particular location by nearby natural or artificial topographic features.
Industry:Weather
The phenomenon during unstable atmospheric conditions caused by the presence of large convective turbulent motions where a smoke plume waves upward and downward like a garden hose. Compare coning, fanning, lofting.
Industry:Weather
The phenomenon where the upper part of a smoke plume diffuses more rapidly upward than the bottom part diffuses downward. This generally occurs when the boundary layer near the ground is more stable than it is aloft. Compare coning, fanning, looping.
Industry:Weather
The photometric equivalent of radiance. Luminance is obtained by integrating spectral radiance weighted by luminous efficiency over the visible spectrum. Compare illuminance.
Industry:Weather
The process by which negative charge centers at successively more distant locations in a thundercloud are “tapped” for discharge by successive strokes of cloud-to-ground lightning.
Industry:Weather
The period during which observations have been maintained at a meteorological station, and which serves as the frame of reference for climatic data at that station. The standard length of record for the purpose of a normal has been fixed by the World Meteorological Organization as 30 years (i.e., three consecutive 10-year periods), which is a reasonable average for the length of a homogeneous record desirable for most of the meteorological elements. Homogeneous records as long as 50 years are rare due to breaks or gradual changes being introduced by changes in the hours of observation, in the observational practices, in the site or instruments used, or by a gradual change in the character of the surrounding country, such as the growth of a city. It is often possible, however, to account for these changes and to construct a composite record that may cover a century or more.
Industry:Weather
The passage of water through the Gulf of Mexico from Yucatan Strait to the Straits of Florida and the connection between the Caribbean and Florida Currents. The Loop Current is part of the western boundary current system of the North Atlantic subtropical gyre and as such is swift flowing, extending to great depth, and prone to instabilities. Its path includes a large northward excursion into the gulf beyond 27°N but retreats to 25°N when shedding an eddy. Eddies drift slowly westward into the central and western Gulf of Mexico.
Industry:Weather
The occurrence of air temperature below 0°C (32°F) that kills annual vegetation without formation of frost crystals on surfaces. See freeze, dry freeze, hard freeze, light freeze.
Industry:Weather
The occurrence of air temperature below 0°C (32°F) that kills some, but not all, annual vegetation. This often occurs in the 0° to −1°C (32°–30°F) range. See freeze.
Industry:Weather
