The Amazon makes its own rain — and kick-starts its own wet season

The Amazon doesn’t just receive rain — it manufactures it. Trees pull water from the soil and release it through their leaves as vapor, a process called transpiration. A single rainforest can pump enough moisture into the air to form clouds and rain again downwind, recycling the same water across the basin many times over.

This moisture forms vast “flying rivers” of vapor that drift over South America. Britannica notes that about half of the Amazon basin’s rainfall comes not from the Atlantic but from the forest’s own evapotranspiration.

NASA scientists found the effect is strong enough to start the wet season itself. Using satellite measurements of water vapor, they showed the southern Amazon’s rainy season begins two to three months before the seasonal winds could bring ocean moisture — triggered by water the trees release. Cut down the forest, and you risk switching off its own rainmaker.