wind [%PREMIUM_LINK%] (wĭnd) Pronunciation Key |
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A current of air, especially a natural one that moves along or parallel to the ground, moving from an area of high pressure to an area of low pressure. Surface wind is measured by anemometers or its effect on objects, such as trees. The large-scale pattern of winds on Earth is governed primarily by differences in the net solar radiation received at the Earth's surface, but it is also influenced by the Earth's rotation, by the distribution of continents and oceans, by ocean currents, and by topography. On a local scale, the differences in rate of heating and cooling of land versus bodies of water greatly affect wind formation. Prevailing global winds are classified into three major belts in the Northern Hemisphere and three corresponding belts in the Southern Hemisphere. The trade winds blow generally east to west toward a low-pressure zone at the equator throughout the region from 30° north to 30° south of the equator. The westerlies blow from west to east in the temperate mid-latitude regions (from 30° to 60° north and south of the equator), and the polar easterlies blow from east to west out of high-pressure areas in the polar regions. See also Beaufort scale, chinook, foehn, monsoon, Santa Ana.