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how deserts are formed?

What is a Desert?

Deserts are areas of the world that are extremely dry. They don't get much rain. Officially a desert is an area that gets less than 10 inches of precipitation a year. Deserts don't necessarily have to be hot. Some of the world's largest deserts are cold deserts located at one of the Earths poles or in a cold area of the world. One thing is for sure, deserts are dry and barren places and lack of vegetations.

Fun Facts about Deserts
  • The nickname for the Rub'al-Khali is the Empty Quarter because there is so little there other than sand.
  • Meerkat Manor was a television series about meerkats in the Kalahari desert.
  • Death Valley, the lowest elevation in the US at 282 feet below sea level, is only 86 miles from Mount Whitney, the highest point in the continuous United States.
  • About 20 percent of the world's land surface is desert.
  • Europe is the only continent with no large deserts.


Causes of desert formation

          The four main causes that contribute to the formation of deserts are:

1. High pressure regions - The Earth is not heated equally by the sun. At the Equator, which receives the most sun's heat, hot air rises creating a zone of low pressure. The air spreads towards the tropics, cools down and descends . Much of the moisture is lost now as rain. As these dry winds sink, they create areas of high pressure where most of the deserts are found - at the Tropics of Cancer and Capricorn. An example of a desert formed by this is the Sahara.
2. Dry air currents - Most rain-carrying currents come from the sea, picking up moisture along the way. The air gets drier and drier inland, therefore creating deserts at places where little rain fall (arid land). These deserts are called continental deserts because of their location inland. They have the most fluctuating temperatures in the world (example: in Gobi, temperatures is between 45ºC in summers and -40ºC in winters).
3. Rain shadow - Some places are sheltered from rain-bearing winds by mountain ranges. The wind rises from the sea to the mountains, cooling and raining on the windward side of the mountain. As it reaches the leeward side of the mountain, the wind is dry, therefore there is little rain. Deserts are formed in the rain shadow of mountains. An example of a desert formed by Rain Shadow is Death Valley, USA.
4. Cold ocean currents - Water is constantly circulating around the oceans as sea currents, which is either warm or cold. Water from polar regions sweeps towards the equator along western coasts of continents. These cold currents cool the air, forcing it to rain over the sea, causing deserts to form at the coast. When warm air currents meets cold seas, moisture reaches the coast by fog. The rainfall does not penetrate inland and formed deserts.

Images of desert









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