The Living World
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The Distribution and Physical Characteristics of Hot Deserts

Distribution

Hot deserts cover approximately 20% of the Earth’s surface and are found on almost all continents. They’re mainly located in a band around the Tropic of Capricorn and the Tropic of Cancer, between approximately 15° – 30° north and south of the Equator. The largest hot desert is the Sahara Desert, which covers an area of more than 9.2 million square kilometres.

Hot deserts are present in North America, South America, Oceania, Africa, the Middle East and Asia. Their prevalence in these regions is due to the specific conditions required to form a hot desert, which are typically found between the two Tropics.

Physical Characteristics

Climate

Hot desert climates are extremely dry and very hot. These deserts are found in areas of high air pressure. When air pressure is high, the air is descending, rather than rising (descending air warms while rising air cools). The air warms, leading to little or no precipitation and a very dry climate.

In addition to high air pressure, hot deserts also experience low moisture. This is due to prevailing winds that often come from land masses and therefore contain little moisture. However, some deserts are in a rain shadow, so they lose access to potential moisture through relief rainfall.

Pressure systems

The high air pressure over hot desert climates is due to global atmospheric pressure systems:

Key Terms

TermDefinition
EquatorAn imaginary line horizontally drawn on the Earth, an equal distance between both poles, dividing the Earth into two hemispheres. It sits on the parallel of latitude 0°. 
Rain ShadowA rain shadow occurs on the leeward side of a mountainous area. The clouds are forced to rise and cool over the mountain, leading to precipitation. As the air descends on the other side, it warms and dries, resulting in less rainfall.
AtmosphereThe layer of gases surrounding the planet.
Tropics of Capricorn and CancerThe Tropic of Cancer is the northernmost latitude at which the sun can be directly overhead. The Tropic of Capricorn is the southernmost latitude where the sun can be directly overhead. They are located at 23.4° north and south, respectively.

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