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UPSC Prelims 1991 · Indian Geography · Monsoon and Climate
Which one of the following winds is not a planetary wind?
- (a) Trade
- (b) Westerly
- (c) Polar Easterly
- (d) Monsoon
Show the answer and explanation
Answer: (d) Monsoon
Monsoons are seasonal (periodic) winds, not planetary.
The idea
Winds are grouped by how regularly they blow and by the scale of their circulation. Planetary winds belong to the broad pressure belts that persist through the year. Periodic winds change with a seasonal or daily cycle, while local winds belong to particular settings.
Why the others are wrong
(a) Trade winds are planetary.
(b) Westerlies are planetary.
(c) Polar easterlies are planetary.
Elimination technique
Trades, westerlies and polar easterlies all belong to the global pressure-belt system. Monsoon is the seasonal member of the list, so it is the odd one out.
Also know
Planetary wind belts shift north and south with the seasons; permanent does not mean fixed in place. Land and sea breezes reverse over a day, while monsoon circulation reverses over the year. Chinook and foehn are warm, dry downslope winds.
🔒 Planetary: trades, westerlies, polar easterlies. Periodic: monsoons, land–sea breezes. Local: loo, chinook, foehn.
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