. . . AND CAUSE RAIN TO FALL

WhEN fresh, tangy scents greet your nostrils in a coniferous forest, you’re smelling airborne substances called terpenes which are crucial to the ability of trees to make it rain. For precipitation to happen, a large group of water molecules must clump together and get heavy enough to fall as raindrops. But they only do this if they can adhere to small particles wafting through the air.

There are lots of these — ash from volcanoes, dust from the desert, tiny salt crystals from the ocean — but, above all, particles actively emitted by plants.

The hotter it is, the more of these terpenes that conifers emit, and they can hit the jackpot with even a small thundercloud, which is capable of dropping 125 million gallons of water on to the thirsty trees below.