2010 General Studies, all questions

UPSC Prelims 2010 · General Studies

Question 107: Geography

What causes wind to deflect toward left in the Southern hemisphere ?

aTemperature
bMagnetic field
cRotation of the earth
dPressure

AnswerThe answer is (c).

Because the Earth rotates, moving air is deflected by the Coriolis force: to the right of its path in the Northern Hemisphere and to the left in the Southern Hemisphere. The deflection is caused by the Earth's rotation. Temperature and pressure differences start the wind moving but do not deflect it, and the Earth's magnetic field has no effect on winds. Remember: the Coriolis effect is zero at the equator and strongest at the poles.

Why each option is right or wrong
  • (a) Temperature differences start winds but do not deflect them.
  • (b) The magnetic field does not affect winds.
  • (c) Right: the rotation of the Earth deflects the wind.
  • (d) Pressure differences drive the wind but do not deflect it.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2010, General Studies, Series A. The paper on upsc.gov.in.