Understanding tropical rainfall

The Intertropical Convergence Zone (ITCZ), also known as the doldrums, is one of the dramatic features of Earth’s climate system. Prominent enough to be seen from space, the ITCZ appears in satellite images as a band of bright clouds around the tropics. Here, moist warm air accumulates in this atmospheric region near the equator, where the ocean and atmosphere heavily interact. Intense solar radiation and calm, warm ocean waters produce an area of high humidity, ascending air, and rainfall, which is fed by converging trade winds from the Northern and Southern Hemispheres. The convected air forms clusters of thunderstorms characteristic of the ITCZ, releasing heat before moving away from the ITCZ — toward the poles — cooling and descending in the subtropics. This circulation completes the Hadley cells of the ITCZ, which play an important role in balancing Earth’s energy budget — transporting energy between the hemispheres and away from the equator.
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