RAS question
The Great Indian Desert (Thar) receives less than:
Correct answer: (A) 25 cm of annual rainfall.
The Great Indian Desert, or Thar Desert, receives less than 25 cm of annual rainfall.
Explanation
The Thar is correctly placed in the lowest rainfall bracket because it is an arid desert region. The NCERT chapter describes the Indian Desert as lying west of the Aravali Hills, with an undulating sandy plain, sand dunes, low vegetation cover and very low rainfall below 150 mm per year. That figure is 15 cm, so it comfortably supports the exam statement that the Thar receives less than 25 cm annually. In Rajasthan, Jaisalmer receives about 20 cm, while the Aravallis run nearly parallel to the monsoon winds and therefore do not block and lift them effectively. Along the coast, the south-west monsoon winds also remain offshore, limiting rainfall over western Rajasthan.
Why the other options are wrong
- (B) 200 cm is a high-rainfall figure and does not match an arid desert that NCERT describes as receiving very low rainfall below 150 mm per year.
- (C) 100 cm is far above the rainfall range implied by the Thar's arid climate and the NCERT figure of below 150 mm per year.
- (D) 50 cm still overstates Thar rainfall, because both the Rajasthan rainfall mechanism and the NCERT source place it below the 25 cm threshold.
Concept
This tests the RAS geography concept of Rajasthan's rainfall distribution and desert aridity. It recurs because Thar rainfall is tied to the Aravalli orientation and the behaviour of the south-west monsoon over western Rajasthan.