Desert Biome : Desert, Location and its Classifications

 Desert and its Classification

• Desert is a biome in which evaporation exceeds precipitation. The rate of evaporation varies with temperature. 

• Desert is likely to develop where the annual precipitation is less than 250 mm. It is important to remember that aridity (or the absence of moisture) is the common characteristic of all deserts, while temperature varies from desert to desert. 

• Deserts may be classified into hot and dry deserts, semi deserts, coastal deserts and cold deserts, based on the amount and distribution of temperature and precipitation.

• Deserts in which sand is in abundance, completely covering the ground and leading to the formation of dunes that resemble wave-like ridges of the ocean surface, are called erg, meaning a sand sea.

• In other deserts, the wind may blow away all the sand, leaving behind closely packed, interlocking angular rock fragments. Such a stony desert is known as reg.

• In some deserts the landscape is dominated by boulders and exposed bedrock. Hamada is the name given to such deserts.

Deserts Location

• Deserts are generally located at the 30 Degree Latitude (in both hemisphere).

• The largest hot deserts, like the Sahara and Arabian deserts, are located in the trade wind belt near the sub-tropical high pressure belts in both the hemispheres. These are places located under the descending limb of the Hadley Cell that dominates the atmospheric circulation in tropical areas. As the air subsides, it warms adiabatically, inhibiting condensation and precipitation.

• Some deserts are located on the leeward side of mountains and the rain shadow effect is responsible for their formation. The Sonoran desert in North America is located to the east of the coastal ranges.

• Deserts are also located in the interior of continents. Their interior location prevents them from receiving moisture from the oceans. The Gobi desert has been formed due to the inland location as well as the rain shadow effect.

• The presence of cold ocean currents also favours the formation of deserts. The formation of the Kalahari desert in Africa and the Atacama desert in South America is aided by the effects of the Benguela and Humboldt currents respectively.

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