Desert Climate: Definition, Characteristics and Economy

Deserts are regions of scanty rainfall that may be Hot like the hot deserts of the Saharan type or Temperate as are the mid-latitude deserts like the Gobi. Hot deserts, located between 15° and 30° N and S, owe their aridity to offshore Trade Winds, while mid-latitude deserts often sit atop plateaus and receive less than 25 cm of rainfall.

Desert Climate: Characteristics and Geography

Hot Desert Climate

• Distribution: Major hot deserts of the world are located on the western coasts of the continent between 15° and 30° N and S.
• Influence of Offshore Trade Winds: The aridity of the hot deserts is mainly due to the effects of off-shore Trade Winds; also called Trade Wind Deserts. 
  • Examples: Sahara Desert, Great Australian Desert, Arabian, Iranian, Thar, Kalahari, Namib, Mohave, Sonoran, Atacama desert. 
• Climate Conditions in Hot Deserts (Trade Wind Deserts)
  • The average summer temperature is around 30°C.
  • Rainfall: scarce (less than 25 cm) and most unreliable.
  • Aridity is high due to subtropical high-pressure belt (descending air), offshore trade winds, desiccating effect of cold currents.
  • Temperature: high throughout the year, coastal deserts due to maritime influence have much lower temperatures; 
  • Diurnal temperature range is very great, frost may occur at night in winters.

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Mid-Latitude Desert Climates

• Distribution: Among the mid-latitude deserts (usually between 30° and 50° N and S of the equator), many are found on plateaus. 
  • Desert interiors, however, experience much higher summer temperatures and winter months are rather cold.
  • Examples: Gobi, Namib, Atacama, Takla Makan, Antarctica, etc.
• Climate conditions in the mid-latitude deserts 
  • They are cut off from the rain-bearing winds; rainfall is less than 25 cm.
  • Occasionally Depressions: may penetrate the Asiatic continental mass or unexpected convectional storms may bring rain in summer and fall in winter.
    • These storms burst suddenly and pour continuously for a few hours over small areas. 
    • However, their violence and suddenness can lead to disastrous flash floods, impacting desert landforms
  • Rainless because of either continentality (Gobi Desert) or rain-shadow effect (Patagonian Desert).
  • Patagonian Desert: It is drier due to its rain-shadow position on the leeward side of the lofty Andes than to continentality.

Vegetation

• Xerophytic Vegetation: Drought-resistant scrubs, grasses and plants;
  • Most desert shrubs have long roots to gather moisture
  • Few or no leaves; foliage is waxy, leathery, hairy, or needle-shaped to prevent moisture loss.
  • Examples: cacti, thorny bushes, wiry grasses, scattered dwarf acacias. 
• Factors Influencing Tree Distribution: Trees are rare except where there’s ample groundwater to support clusters of date palms. 
  • Western coastal deserts, like the Atacama Desert, have sparse vegetation due to cold currents. 
  • Intense evaporation increases soil salinity, forming hard pans. 
  • Lack of Humus: Moisture absence slows decomposition, resulting in humus-deficient soils. 
  • Desert shrubs have long roots spaced out to gather moisture, with foliage designed to minimize water loss. 
  • Seeds of many grasses and herbs have thick, tough skins to protect them during dormancy.

Economy

• Agriculture and Settlements: The Nile River enabled ancient Egyptians to cultivate crops 5,000 years ago, with modern dams like the Aswan and Sennar further enhancing agriculture. 
  • Desert dwellers rely on rivers like the Indus, Tigris-Euphrates, and Colorado to sustain farming. 
  • Settlements: thrive around oases, and depressions where underground water surfaces. Some, like Morocco’s Tafilalet Oasis, span vast areas. 
    • Oases are often enclosed by walls to shield from dust storms. 
    • Date palms are crucial, providing both local consumption and export. 
  • Crops: Maize, barley, wheat, cotton, sugarcane, fruits, and vegetables.
• Minerals
  • Gold Mining: in the Great Australian Desert (e.g., Kalgoorlie, Coolgardie); Diamonds and copper in Kalahari; Sodium nitrate extraction in Atacama.
  • Silver: Silver in Mexico, 
  • Uranium: in Utah, copper in Nevada
  • Oil Exploration: In Sahara and Arabian Deserts (Saudi Arabia, Iran, Iraq, Kuwait, Algeria, Libya, Lebanon, and Nigeria)
• Tribes: Bedouin (Arabs), Bushman (Kalahari),  Bindibu (Australia), Tuaregs (Sahara), Gobi Mongols (Gobi)

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Conclusion

Desert climates, whether hot like the Sahara or temperate like the Gobi, are dry with sparse vegetation. Major hot deserts are situated in areas influenced by subtropical high-pressure belts, resulting in permanent drought conditions. Human settlements rely on water sources like rivers and oases for agriculture, with oases being crucial for cultivation and habitation. The desert economy includes agriculture, mineral extraction, and nomadic tribes, each playing a role in the desert’s unique way of life.

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