Drought

Drought
A Drought is a period or condition of unusually dry weather within a geographic area where rainfall is normally present. During a drought there is a lack of precipitation. Droughts occur inall climatic zones. However, its characteristics vary significantly from one region to another.

Drought usually results in a water shortage that seriously interferes with human activity.Water-supply reservoirs empty, wells dry up, and crop damage ensues. Its seriousness depends on the degree of the water shortage, size of area affected, and the duration and warmth of the dry period. In manyunderdeveloped countries, such as India, people place a great demand on water supply. During a drought period there is a lack of water, and thus many of the poor die.

Most precipitation depends onwater vapor carried by winds from an ocean or other source of moisture. If these moisture-carrying winds are replaced by winds from a dry region, or if they are modified by downward motion, as in thecenter of an anticyclone, the weather is abnormally dry and often persistently cloudless. If the drought period is short, it is known as a dry spell. A dry spell is usually more than 14 days withoutprecipitation, whereas a severe drought may last for years.

Statistics indicate that every 22 years a major drought occurs in the United States, most seriously affecting the midwestern states. Thedrought of 1933-35, during which large areas of the Great Plains became known as the Dust Bowl, is an example of a disastrous drought that took place in the United Staes. The effect of the drought wasbrought about by overcropping, overpopulation, and lack of relief measures.

Although drought cannot be reliably predicted, certain precautions can be taken in drought-risk areas. These includeconstruction of reservoirs to hold emergency water supplies, education to avoid overcropping and overgrazing, and programs to limit settlement in drought-prone areas. The Southern Africa Development...