2011 GS Paper I, all questions

UPSC Prelims 2011 · GS Paper I

Question 89: Geography

Westerlies in southern hemisphere are stronger and persistent than in northern hemisphere. Why ?

  1. 1.Southern hemisphere has less landmass as compared to northern hemisphere.
  2. 2.Coriolis force is higher in southern hemisphere as compared to northern hemisphere

Which of the statements given above is/are correct ?

a1 only
b2 only
cBoth 1 and 2
dNeither 1 nor 2

AnswerThe answer is (a).

The westerlies blow from the subtropical highs towards the sub-polar lows. In the southern hemisphere the latitudes of about 40 to 60 degrees are almost all ocean, so there is little land or mountain to slow the wind, which gives strong, steady winds, the Roaring Forties and Furious Fifties. In the north, land masses break and weaken them. The Coriolis force depends on latitude and is the same in both hemispheres, differing only in direction.

  • 1. Less land in the south means less friction and steadier westerlies.
  • 2. Coriolis force does not differ in strength between hemispheres at the same latitude.

How you could have got this

  1. If you were sure statement 1 is correct, (b) and (d) go: each of them leaves 1 out.

    What you needed to know: Less land in the south means less friction and steadier westerlies.

  2. Then, if you were sure statement 2 is not correct, (c) goes: it includes 2.

    What you needed to know: Coriolis force does not differ in strength between hemispheres at the same latitude.

Only (a) is left. This one needs every statement.

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) Right: the southern hemisphere has less land, so less friction.
  • (b) Coriolis force is not higher in the south; it differs only in direction.
  • (c) Statement 2 is wrong, so 'both' fails.
  • (d) Statement 1 is correct, so 'neither' fails.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2011, General Studies Paper I, Series A. The paper on upsc.gov.in.