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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, ...
In meteorology, an area of high pressure, referring to a maximum of atmospheric pressure in two dimensions (closed isobars) in the synoptic surface chart, or a maximum of height (closed contours) in the constant-pressure chart. Since a high is, on the synoptic chart, always associated with anticyclonic circulation, the term is used interchangeably with anticyclone. Compare low.
Industry:Weather
In Nordenskjöld's climatic classification (1928), the climate of those parts of the world where the average temperature of the warmest month is below 0°C. It is equivalent, therefore, to the perpetual frost climate of W. Köppen (1918), and to C. W. Thornthwaite's frost climate (1931). See polar climate.
Industry:Weather
In meteorology, a departure from the usual decrease or increase with altitude of the value of an atmospheric property; also, the layer through which this departure occurs (the “inversion layer”), or the lowest altitude at which the departure is found (the “base of the inversion”).
Industry:Weather
In general (mathematics), the locus of one end of a variable vector as the other end remains fixed. A common hodograph (or hodogram) in meteorology represents the vertical distribution of the horizontal wind.
Industry:Weather
In climatology, a day on which the maximum air temperature in a thermometer shelter does not rise above 0°C (32°F), and ice on the surface of water does not thaw. This term is not used in the United States, but is used in the United Kingdom, throughout most of Europe, and probably in many other parts of the world.
Industry:Weather
In C. W. Thornthwaite's 1931 climatic classification, a region in which the precipitation effectiveness of its climate produces a definite type of biological consequence, in particular the climatic climax formations of vegetation (rain forest, tundra, etc. ). Five main classes of humidity province are distinguished, bounded by values of precipitation effectiveness index (P–E index): 1) wet or rain forest; 2) humid or forest; 3) subhumid or grassland; 4) semiarid or steppe; and 5) arid or desert. Thornthwaite (1948) used values of moisture index to limit similar but purely climatic (nonbiological) zones as follows: 1) perhumid; 2) humid; 3) subhumid; 4) semiarid; and 5) arid. The moist climates are those with a positive moisture index; dry climates have negative values. Compare hyetal region, climatic province, temperature province.
Industry:Weather
In artificial neural networks, a layer of nodes between the input and output layers that contains the weights and processes data. The values within the hidden layer are constantly adjusted during the training of the neural network, until the desired output is reached.
Industry:Weather
In atmospheric electricity, the process by which neutral atmospheric molecules (small ions) or other suspended particles (mainly large ions) are rendered electrically charged chiefly by collisions with high-energy particles. Cosmic rays and radioactive decay are the main sources of atmospheric ionization. In the lower atmosphere, decay electrons of mu-mesons plus alpha particles from radioactive gases, as well as beta particles and gamma rays, serve to ionize air molecules. The rate at which these agents ionize the air is expressed in units of one ion pair per cubic centimeter per second, symbolized by I. Cosmic rays at sea level yield about 2I, both over land and at sea. Radioactive gases contribute about 5I over land areas at sea level, while radioactive materials in the soil and rocks themselves yield about 4I. At heights above about 5 km, only cosmic rays provide significant ionization, and this contribution finally reaches a maximum at about 13 km, above which the rate decreases, due to decreasing air density and consequent lack of target molecules for the cosmic rays. See photoionization.
Industry:Weather
