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Area or system of high atmospheric pressure that has a characteristic pattern of air circulation, with subsiding air and horizontal divergence of the air near the surface in its central region. Winds are generally light because of small pressure gradients; they flow clockwise in the northern hemisphere and anticlockwise in the southern hemisphere. A temperature inversion is common at the base of the air subsidence, and this restricts the vertical development of cloud. Weather conditions are generally settled. Cold anticyclones form over continents in winter and over polar areas at any time, accompanied by strong inversions: in the clear air, pronounced frosts and very cold surface conditions result. Warm anticyclones (so called because of the warm, subsided air aloft) over land areas typically bring spells of settled and often warm weather. See also anticyclonic gloom.

Subjects: Earth Sciences and Geography.

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