- 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 process of initiation of a new phase in a supercooled (for liquid) or supersaturated (for solution or vapor) environment; the initiation of a phase change of a substance to a lower thermodynamic energy state (vapor to liquid condensation, vapor to solid deposition, liquid to solid freezing). In nature, heterogeneous nucleation is the more common where such a change takes place on small particles of different composition and structure. Homogeneous nucleation occurs when the change of state centers upon embryos that exist in the same initial state as the changing substance. In this case, the nucleation system contains only one component, and it is termed homogeneous nucleation. In meteorology, particularly in cloud physics, a number of types of nucleation are of interest. The process by which cloud condensation nuclei initiate the phase change from vapor to liquid is important in all cloud formation problems. The physical nature of freezing nuclei that may be responsible for the conversion of drops of supercooled water into ice crystals is critically important in precipitation theory, as is the clarification of the role of homogeneous nucleation near −40°C. Thermodynamically, all nucleation processes involve free energy decrease associated with the bulk phase change and the free energy increase associated with the creation of new interfaces between phases.
Industry:Weather
A term used to describe the surface cooling that might result from the emission of extensive clouds of smoke (from burning cities, fuel sites, and forests) following the detonation of hundreds of warheads in a nuclear exchange.
Industry:Weather
A short-term weather forecast, generally for the next few hours. The U. S. National Weather Service specifies zero to three hours, though up to six hours may be used by some. Compare short-range forecast, very short-range forecast, long-range forecast.
Industry:Weather
(Often contracted nor'wester. ) A northwesterly wind (as Canterbury northwester). See also kal Baisakhi.
Industry:Weather
A northerly wind; in general, a cold windstorm from the north. The term has several specific applications: 1) In the southern United States, especially in Texas (Texas norther), in the Gulf of Mexico, in the Gulf of Panama away from the coast, and in Central America (norte), the norther is a strong cold wind from between northeast and northwest. It occurs between November and April, freshening during the afternoon and decreasing at night. It is a cold air outbreak associated with the southward movement of a cold anticyclone. It is usually preceded by a warm and cloudy or rainy spell with southerly winds. The norther comes as a rushing blast and brings a sudden drop of temperature of as much as 25°F in one hour or 50°F in three hours in winter. 2) The California norther is a strong, very dry, dusty, northerly wind that blows in late spring, summer, and early fall in the valley of California or on the West Coast when pressure is high over the mountains to the north. It lasts from one to four days. The dryness is due to adiabatic warming during descent. In summer it is very hot. 3) The Portuguese norther is the beginning of the trade wind west of Portugal. 4) Norther is used for a strong north wind on the coast of Chile that blows occasionally in summer. 5) In southeast Australia, a hot dry wind from the desert is called a norther. See also chocolatero, tehuantepecer; compare burster, pampero.
Industry:Weather
A northeast wind, particularly a strong wind or gale. Two well-known examples are the black northeaster of Australia and New Zealand and the northeast storm of the east coast of North America.
Industry:Weather
The steep water-temperature gradient between the Gulf Stream and 1) the Slope Water inshore of the Gulf Stream or 2) the Labrador Current north of the Gulf Stream.
Industry:Weather
A cyclonic storm of the east coast of North America, so called because the winds over the coastal area are from the northeast. They may occur at any time of year but are most frequent and most violent between September and April. Northeast storms usually develop in lower–middle latitudes (30°–40°N) within 100 miles east or west of the coastline. They progress generally northward to northeastward and typically attain maximum intensity near New England and the Maritime Provinces. They nearly always bring precipitation, winds of gale force, rough seas, and, occasionally, coastal flooding to the affected regions.
Industry:Weather
