Traditional Indian Seasons

The map is a choropleth of India, shaded to show the total rainfall received during the southwest monsoon months of June through September. Seven bands of shading run from “Above 400 cm” down through 200–400, 100–200, 60–100, 40–60, 20–40, and finally 0–20 cm. A scale bar at the bottom gives the distance reference of 0–600 km, and the graticule (the latitude–longitude grid) is drawn across the whole country so you can locate any region precisely.

What the shading immediately reveals is how unevenly the monsoon delivers its rain. The heaviest totals, above 400 cm, hug the western coast along the Western Ghats and also cover the hills of northeast India, including the Meghalaya plateau. A second zone of very heavy rain runs along the sub-Himalayan belt in the north. From these cores, rainfall tapers off in steps: the 200–400 cm band flanks the Ghats and the Himalayan foothills, while the 100–200 cm band spreads across much of the eastern and central parts of the peninsula.

The dry story is just as important. A large patch over the Deccan interior, lying in the rain shadow of the Western Ghats, falls into the 40–60 cm or even 20–40 cm bands. The northwest desert, Rajasthan and adjoining areas, shows the lowest totals of all, in the 0–20 cm band. So the map is not a uniform wash of blue; it is a sharp contrast between windward coasts and hills that receive enormous rain and the leeward, interior, and desert tracts that stay parched even during the monsoon months. …