| Section A | A index | 381-389 of 917 terms |
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Alberta low—A low that originates centered on the eastern slope of the Canadian Rockies in the province of Alberta, Canada. Formerly, it was thought that such lows actually originated (more or less independently) over this location. It is now recognized that depressions moving inland from the Pacific are the actual parent systems. Alberta lows appear as these systems enhance, or are enhanced by, the dynamic trough that is a typical, almost semipermanent, feature of this region. See Colorado low, Alberta clipper.
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Aleutian Current—(Also called the Subarctic Current.) The southern, eastward flowing current of the subpolar gyre in the North Pacific. It is fed by the outflow from the Oyashio and lies north of the North Pacific Current, with which it establishes the polar front in the west and experiences much water exchange as it proceeds eastward. As it approaches the coast of North America, it divides to form the northward flowing Alaska Current and the southward flowing California Current.
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Aleutian low—The low pressure center located near the Aleutian Islands on mean charts of sea level pressure. It represents one of the main centers of action in the atmospheric circulation of the Northern Hemisphere. The Aleutian low is most intense in the winter months; in summer it is displaced toward the North Pole and is almost nonexistent. On a daily basis, the area of the Aleutian low is marked by alternating high and low pressure centers, moving generally to the eastward; it is not the scene of an intense stationary low. Normally the depth of intensity of the low pressure areas exceeds the intensity of the high pressure areas, so that the region is one of low pressure on the average. The travelling cyclones of subpolar latitudes usually reach maximum intensity in the area of the Aleutian low. The Aleutian low and its counterpart in the Atlantic Ocean, the Icelandic low, compose the Northern Hemisphere's subpolar low pressure belt.
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Alexander's dark band—The dark region of the sky seen between the primary and secondary rainbows.It is named after Alexander of Alphrodisias, the first person known to have commented upon it. He was the head of the Lyceum from 198 to 211 A.D.
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Alfvén wave—(Also magnetohydrodynamic wave, hydromagnetic wave.) A transverse wave propagating along a magnetic field in an electrically conducting fluid (or plasma). This kind of wave does not exist in gases or fluids that are not ionized or in a plasma free from a magnetic field. The dynamics of such waves are analogous to those in a vibrating string.
Cowling, T. G., 1976: Magnetohydrodynamics, Ch. 3
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Algerian Current—A narrow intense current along the Algerian coast in which the transport of water from the Atlantic Ocean into the Mediterranean Sea is concentrated. It originates from the Almeria–Oran front and for the first 300 km is less than 30 km wide, with average speeds of 0.4 m s−1 and maximum speeds of 0.8 m s−1.
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algorithm—A fixed step-by-step procedure to accomplish a given result; usually a simplified procedure for solving a complex problem; also a full statement of a finite number of steps.
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