The wind that changes sides, and brings the rain to India, Africa, Australia and Arizona.
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A monsoon is a big wind that changes direction with the seasons. Switch between summer and winter in India, and watch the wind turn round. (A simplified picture.)
Land heats up faster than the sea. In summer the hot air over the land rises, and wet sea air rushes in. In winter the land cools, and the wind blows back out. It’s like a sea breeze as big as a country!
Most of India is dry in winter. But on the south-east coast, round Chennai, the winter wind brings the main wet season. It blows from the north-east over the warm Bay of Bengal, picks up water, and drops it on the coast. (A simplified picture.)
In summer, the land in West Africa heats up, and wet wind blows in from the Atlantic Ocean. The Sahel, south of the Sahara, gets most of its rain from June to September. (A simplified picture.)
Make a guess first. Then tap the button to see Darwin, in the far north of Australia, in January.
Guess, then try: Is Darwin wetter in January or in July? (January / July)
North America has a monsoon too! In summer the land in Mexico and the US south-west gets very hot. The wind turns, and brings wet air from the Gulf of California and the Pacific. Storms grow most afternoons. (A simplified picture.)
You visited four monsoons: India, West Africa, northern Australia and Arizona.
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The globe pictures are simplified to show the idea. Earth images: NASA Blue Marble (public domain).