What causes the smell after rain?

Most people notice a distinctive smell in the air after it rains. It’s frequently linked with spring, as the smell of fresh cut grass is associated with summer. You’ll find it in a lot of poetry and also on many inspirational lists of things to be happy about. But what causes it?

As it turns out, the smells people associate with rainstorms can be caused by a number of things. One of the more pleasant rain smells, the one we often notice in the woods, is actually caused by bacteria! Actinomycetes, a type of filamentous bacteria, grow in soil when conditions are damp and warm. When the soil dries out, the bacteria produces spores in the soil. The wetness and force of rainfall kick these tiny spores up into the air where the moisture after a rain acts as an aerosol (just like an aerosol air freshener).