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In meteorology, an anticyclone is a weather phenomenon associated with atmospheric high pressure. In the northern hemisphere an anticyclone rotates in the clockwise direction, while it rotates counterclockwise in the southern hemisphere. The rotation is caused by the movement of colder higher pressure air that is moving away from the poles towards the equator being affected by the rotation of the earth.

Anticyclones generally bring fair weather and clear skies as the dynamics of an anticyclone lead to downward vertical movement which suppresses convective activity and generally lowers the mean relative humidity, in contrast to the upward vertical movement in a cyclone. However as the anticyclone moves over the earth surface it may heat up locally, acquire water from the land or oceans or encounter warmer wet air. Local geography may cause a range of localised weather phenomena specific to anticyclones, while the interaction of the different air masses, which occurs at weather fronts , may cause a range of weather events.

See also: cyclone, Coriolis force, atmospheric pressure.

Last updated: 03-13-2005 10:35:26