- Industry: 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, ...
An occluded front in which the occlusion process has been hastened by the retardation of the warm front along the windward slopes of a mountain range.
Industry:Weather
Precipitation caused or enhanced by one of the mechanisms of orographic lifting of moist air. Examples of precipitation caused by mountains include rainfall from orographic stratus produced by forced lifting and precipitation from orographic cumuli caused by daytime heating of mountain slopes. Many of the classic examples of locations having excessive annual precipitation are located on the windward slopes of mountains facing a steady wind from a warm ocean. As another example, wintertime orographic stratus (cap clouds) often produce the major water supply for populated semiarid regions such as the mountainous western United States, and as a result these cloud systems have been a target of precipitation enhancement, cloud-seeding projects intended to produce snowpack augmentation. Orographic precipitation is not always limited to the ascending ground, but may extend for some distance windward of the base of the barrier (upwind effect), and for a short distance to the lee of the barrier (spillover). The lee side with respect to prevailing moist flow is often characterized as the dry rain shadow. See seeder–feeder.
Industry:Weather
As commonly used, same as orographic precipitation. See rainfall.
Industry:Weather
The freezing level for precipitation formed by orographic lifting; the elevation above which rain or drizzle turns to snow.
Industry:Weather
A storm that is produced or significantly enhanced by mountain effects such as orographic lifting or lee cyclogenesis.
Industry:Weather
Atmospheric vortex or whirlwind produced by flow over or past mountains and other obstacles. Orographic vortices exist over a wide range of scales and orientations, from eddies of a few tens to a few hundreds of meters across, oriented in any direction, and shed by individual peaks or other topographic obstacles, to synoptic-scale cyclones, vertical vortices that form or intensify in the lee trough downwind of mountain-range scale barriers (see lee cyclogenesis). Eddies of several hundred meters to a few tens of kilometers across (the larger scale representing approximately the scale of the mountain producing them) contribute to aircraft turbulence and enhance damage during downslope windstorm conditions. They often are the result of periodic shedding from the obstacle that produced them. Especially strong vertical vortices have been called “mountainadoes,” indicating a resemblance to mountain tornadoes. Under strong convective heating conditions vortices spawned in the mountains sometimes continue downwind over the heated plains and participate in the initiation of dust devils.
Industry:Weather
Wind flow caused, affected, or influenced by mountains. Orographic effects include both dynamic, in which mountains disturb or distort an existing approach flow, and thermodynamic, in which heating or cooling of mountain-slope surfaces generates flow. Dynamic effects include aerodynamic obstacle effects, mountain waves, channeling, orographic blocking, and processes leading to foehn, bora, and gap winds. Thermodynamic effects include anabatic winds, katabatic winds, valley breezes, and mountain breezes. See also mountain–valley wind systems, mountain–plains wind systems.
Industry:Weather
In radar, a pair of transmitting and receiving antennas, or a single antenna used for transmission and reception, designed for measuring the copolarized signal and the cross- polarized signal. See dual-channel radar.
Industry:Weather
A stormy north to northeast wind in the Gulf of Lions off the southern coast of France.
Industry:Weather
In Japan, a dry, northwesterly bora descending the mountains of central Honshu onto the Kanto Plain in winter. This wind is strong, usually exceeding 10 m s<sup>−1</sup>.
Industry:Weather
