THE SMELL OF RAIN.

THE SMELL OF RAIN. Tom Skilling, the weatherman for the Chicago Tribune, answers a reader’s question: what causes the smell of rain? Moisture can cause plants to release odors; Pine forests release a substance used in perfumes. Warmth, high humidity, and lowering pressure, which come before rain, can also cause the release of odors by plants. And moisture seeping into the earth can push aromatic gases released by soil bacteria into the air. What strikes me most is that I have lived so many years without ever wondering about the smell of rain.