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Drought, condition of abnormally dry weather within a geographic region where some rain might usually be expected. A drought is thus quite different from a dry climate which designates a region that is normally, or at least seasonally, dry. Athough the quantity of ....

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.... of about 15°-20° and in areas bordering the permanently arid regions of the world. Lands that are permanent arid is a characteristic of those areas where warm, tropical air masses, in descending to earth, become hotter and drier. When a poleward shift in the west ocurrs, the high-pressure, anticyclonic conditions of the permanently arid regions hit each other on areas that are normally used to seasonally wet low-pressure weather and a drought follows. A southward shift in the western winds causes the most severe drought of the 20th century, the one that struck the African region, Sahel for 12 years starting in 1968. Statistics indicate that roug ....