Local Winds: Sea Breezes
Although global winds are important in determining the prevailing winds in a given area, local climatic conditions may wield an influence on the most common wind directions.
Local winds are always superimposed upon the larger scale wind systems, i.e. the wind direction is influenced by the sum of global and local effects. When larger scale winds are light, local winds may dominate the wind patterns.
Sea Breezes
Sea breeze cartoon Land masses are heated by the sun more quickly than the sea in the daytime. The air rises, flows out to the sea, and creates a low pressure at ground level which attracts the cool air from the sea. This is called a sea breeze. At nightfall there is often a period of calm when land and sea temperatures are equal.
At night the wind blows in the opposite direction. The land breeze at night generally has lower wind speeds, because the temperature difference between land and sea is smaller at night.
The monsoon known from South-East Asia is in reality a large-scale form of the sea breeze and land breeze, varying in its direction between seasons, because land masses are heated or cooled more quickly than the sea.
© Copyright 1997-2003 Danish Wind Industry Association
Updated 1 June 2003
http://www.windpower.org/en/tour/wres/localwin.htm
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