Pragnya IAS · Map 45 · Climate & environment
India: annual rainfall map study
Distinguish the annual rainfall map from the seasonal one and learn the classic isohyet values.
STUDY NOTE 1
Annual versus seasonal
Annual totals add the retreating monsoon and winter rain, which is why Tamil Nadu’s annual map looks wetter than its June–September map.
STUDY NOTE 2
Key isohyets
The 100 cm line splits “humid enough for rice without irrigation” from drier tracts; 200 cm marks the evergreen belt; 25 cm encloses the true desert.
STUDY NOTE 3
Variability matters
Regions with low mean rainfall also have high year-to-year variability — the arid zone’s average hides frequent drought years.
Map reading task
Draw the 25, 50, 100 and 200 cm isohyets and label one region between each pair.
Map key · Reference locations
What does this india: annual rainfall lesson explain?
Annual totals add the retreating monsoon and winter rain, which is why Tamil Nadu’s annual map looks wetter than its June–September map.
UPSC map practice & Geography Optional connection
For UPSC Prelims, pair the location with its state, neighbouring relief and relevant geographic process. For GS I and Geography Optional Indian geography revision, use a simple labelled sketch to explain the relationship rather than replacing the answer with place names. These are Pragnya-authored exercises, not official UPSC previous-year questions.
References & map credits
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