UPSC Prelims 2011 · Question 34 of 100
UPSC Prelims 2011 question on Desert Belt Formation
- ExamUPSC CSE
- Year2011
- PaperGeneral Studies Paper I
- SubjectGeography
- TopicClimatology
- DifficultyMedium
- TypeStatement
What could be the main reason/reasons of the formation of African and Eurasian desert belt?
1. It is located in the sub-tropical high pressure cells.
2. It is under the influence of warm ocean currents.
Which of the statements given above is/are correct in this context?
Show answer
Answer: A. 1 only
Verdict
Correct Answer: 1 only
Analysis
The African and Eurasian desert belt is mainly formed because it lies in the sub-tropical high-pressure belt, where dry descending air prevents rainfall.
Statement by statement
1. It is located in the sub-tropical high-pressure cells — Correct
Around 20°–30° north and south latitudes, air descends as part of the Hadley Cell circulation. This descending air becomes warm and dry, creating high pressure.
As a result, cloud formation is suppressed and rainfall becomes very low. This explains the presence of deserts such as the Sahara, Arabian and Thar deserts.
2. It is under the influence of warm ocean currents — Incorrect
Warm ocean currents usually increase evaporation and moisture, which may support rainfall.
Desert formation is more commonly associated with cold ocean currents, which cool the air above them and reduce its ability to rise and form rain clouds. For example, the Canary Current influences the western Sahara region.
Extra UPSC Info
Major hot deserts are generally found near 20°–30° latitudes.
Desert formation is linked with descending air, high pressure and low rainfall.
Other factors include continentality, rain-shadow effect and offshore trade winds.
Cold currents help form coastal deserts such as the Atacama and Namib deserts.
The Thar Desert is influenced by subtropical high pressure, continentality and weak monsoon penetration.
Final Takeaway
The main reason for the African-Eurasian desert belt is its location in the sub-tropical high-pressure cells. Warm ocean currents are not the cause. Therefore, only statement 1 is correct.