India: Climate, Soils and Natural Vegetation
Domain 7: India - Climate, Soils and Natural Vegetation
This domain connects the monsoon system to rainfall patterns, soil formation and vegetation belts. Expect cause–effect questions: why a place is wet or dry, why a soil behaves as it does, and which vegetation matches which rainfall.
Core rules
- Monsoon: seasonal reversal of winds. Summer heating creates low pressure over north-west India; the ITCZ shifts; moist south-west winds bring rain. The break in the monsoon is a shift of the rain belt, not the end of the season.
- Seasons: cold weather, hot weather, south-west monsoon and retreating monsoon. Western disturbances bring winter rain to north-west India; cyclones affect the east coast, especially in October–November.
- Soils: alluvial (fertile, transported), black or regur (clay-rich, moisture-retentive, from lava), red (iron-rich, often acidic), laterite (leached, poor for most crops), arid, forest and mountain soils.
- Vegetation: tropical evergreen (heavy rain), deciduous (monsoon), thorn (dry), montane (altitude), mangrove (tidal).
Worked example
A station on the windward Western Ghats receives over 250 cm of rain, while a station 80 km to the leeward receives about 60 cm. The moist south-west monsoon is forced up the Ghats, cools and rains; descending air on the leeward side warms and dries. This is the rain-shadow effect. Reasoning: relief, not distance from the sea alone, explains the sharp contrast.
Traps
Do not say black soil is freshly erupted lava; it is formed from weathered basaltic lava. Do not call laterite naturally fertile. Do not assume all of India gets south-west monsoon rain; Tamil Nadu's main rainy season is the north-east monsoon. Do not confuse winter rain from western disturbances with monsoon rain.