UPSC Prelims 2015 · GS Paper I
Question 66: Geography
Consider the following statements :
- 1.The winds which blow between 30° N and 60° S latitudes throughout the year are known as westerlies.
- 2.The moist air masses that cause winter rains in North-Western region of India are part of westerlies.
Which of the statements given above is/are correct?
AnswerUPSC’s answer is (b).
Westerlies are the prevailing winds blowing from the west in the middle latitudes, between about 30 and 60 degrees in both the northern and southern hemispheres, not between 30 N and 60 S, so statement 1 is wrong. The western disturbances that bring winter rain to north-western India are moist air masses carried by the westerlies, so statement 2 is correct.
- 1. Westerlies blow between 30 and 60 degrees in each hemisphere, not from 30 N to 60 S.
- 2. Western disturbances carried by westerlies bring winter rain to north-western India.
How you could have got this
- If you were sure statement 1 is not correct, (a) and (c) go: each of them includes 1.
What you needed to know: Westerlies blow between 30 and 60 degrees in each hemisphere, not from 30 N to 60 S.
- Then, if you were sure statement 2 is correct, (d) goes: it leaves 2 out.
What you needed to know: Western disturbances carried by westerlies bring winter rain to north-western India.
Only (b) is left. This one needs every statement.
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) Wrong: the statement's latitude range is incorrect; it should be 30 to 60 in each hemisphere.
- (b) Correct: the winter rains of north-western India come from westerlies; statement 1 has the wrong range.
- (c) Wrong: statement 1 gives the wrong latitudes.
- (d) Wrong: statement 2 is correct.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2015, General Studies Paper I, Series A. The paper on upsc.gov.in.