Science, Tech & Environment

Amazon Stories: Rainmaking

"The World's" Alex Gallafent visited Brazil's Cuieras Amazon Reserve, where he reports on the large-scale biosphere-atmosphere experiment in the forest, and how, according to many scientists, the region will be a possible tipping point for pushing the world into much warmer temperatures.

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The Amazon rain forest acts like a giant air conditioner for the equatorial zone. When rain falls on the forest, much of it gets caught by the foliage up at the top. But what gets through the canopy and reaches the soil down below is taken up by the roots. The water is drawn up from the roots to the leaves above, where it warms up and evaporates. This water vapor combines with tiny solid particles in the air to create rain. The solid particles are created when organic gases produced by the foliage in the forest are transformed by sunlight into small crystals.

PRI's "The World" is a one-hour, weekday radio news magazine offering a mix of news, features, interviews, and music from around the globe. "The World" is a co-production of the BBC World Service, PRI and WGBH Boston. More "The World."