UPSC Prelims 2002 · General Studies

Question 149: Geography

Assertion (A): The surface winds spiral inwards upon the centre of the cyclone. Reason (R): Air descends in the centre of the cyclone.

aBoth A and R are individually true and R is the correct explanation of A

bBoth A and R are individually true but R is not a correct explanation of A

cA is true but R is false

dA is false but R is true

AnswerThe answer is (b).

Assertion A is true: surface winds blow inward and spiral towards the centre of a cyclone, because of the pressure gradient and the Coriolis force. Reason R is true for the eye of a tropical cyclone, where air sinks and the weather is calm, but it is not why the winds spiral inward; the inward flow is caused by the low pressure at the centre. So both are true, but R does not explain A.

A. Surface winds spiral inwards on the cyclone's centre.
R. Air descends in the eye of a tropical cyclone, but this does not explain the inward spiral.

How you could have got this

If you were sure statement 1 is correct, (d) goes. Then judge the second statement; if it is correct too, decide whether it explains the first.

This follows an unofficial answer: UPSC has not published its key for this year, and if that answer is wrong, so is this path.

Which options go is worked out from UPSC’s key and the options, not by a model.

Why each option is right or wrong

(a) R does not explain A, so this option fails.
(b) Right: both true, but R is not the explanation.
(c) R is accepted as true, so this option fails.
(d) A is true, so this option fails.

Worth knowing: R is true only for the eye of a tropical cyclone; air rises at the centre of a temperate cyclone, so (c) is arguable.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2002, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.