1997 General Studies, all questions
UPSC Prelims 1997 · General Studies
Question 10: Geography
The January isotherm taken as a basis for dividing India into tropical and sub-tropical zones is
a21 °C
b18 °C
c12 °C
d15 °C
AnswerThe answer is (b).
The 18°C January isotherm is the line used to separate the tropical south of India from the sub-tropical north. Where the coldest month stays at or above 18°C, the climate counts as tropical, which is also the cut-off for tropical climates in Koppen's scheme. Where winter months are cooler, the climate is sub-tropical. Remember 18°C as the tropical threshold.
Why each option is right or wrong
- (a) 21°C is higher than the standard threshold and is not the dividing line.
- (b) Right: 18°C in January separates tropical from sub-tropical India.
- (c) 12°C is not used as the tropical boundary.
- (d) 15°C is not the standard threshold either.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1997, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.