concept

Hadley cell

The largest loop of atmospheric circulation, filling the tropics: warm moist air rises at the equator, dumps its rain as it cools, drifts poleward high up, and sinks back down as dry air near 30° latitude. The rising branch makes tropical rainforests; the sinking branch makes the great deserts. The cell's width depends on how fast the world spins: slower rotation widens it, pushing both the wet belt and the dry belt farther from the equator.