Environment · Aerosols, Black Carbon & Cloud Effects
The concept being tested: Dust particle distribution across climate and wind zones.
Consider the following statements: Statement I: The amount of dust particles in the atmosphere is more in subtropical and temperate areas than in equatorial and polar regions. Statement II: Subtropical and temperate areas have less dry winds. Which one of the following is correct in respect of the above statements?
Dust content in the atmosphere depends on aridity and wind action, not on distance from the equator. NCERT's Fundamentals of Physical Geography notes that subtropical and temperate latitudes — the belt of hot deserts, semi-arid steppes and continental interiors — carry far more suspended dust than equatorial or polar regions. The equatorial belt is constantly humid, with frequent convectional rain washing dust out of the air almost as fast as it rises. Polar regions are ice or snow covered, leaving little loose material for wind to lift. So Statement I is correct. Statement II reverses the actual mechanism: subtropical and temperate zones are dustier precisely because they experience frequent dry winds blowing over deserts and open, exposed plains, not because they have less dry wind. That makes Statement II factually wrong, which fixes the answer.
What UPSC was testing
This is a two-statement 'does II explain I' format, and the trap is that Statement II sounds like a plausible cause even though it states the exact opposite of the real mechanism — aspirants who don't recall that dry winds, not their absence, generate dust are likely to misjudge it as true or as explaining Statement I.
How often this comes up
This concept has appeared 11 times in UPSC Prelims General Studies Paper I between 2015 and 2025 — in 2018, 2019, 2022, 2024 and 2025.
The option-by-option autopsy for this question — why each of the other three is wrong, and which neighbouring concept each one was built from — is in the app.
Other past-year questions touching Aerosols, Black Carbon & Cloud Effects.