The science behind the smell of rain

The science behind the smell of rain

You know the smell. It’s there every time the first fat raindrops hit the ground—a distinctive, earthy scent that suffuses the air, an aroma that speaks of the changing seasons and promises relief from stifling summer heat. There’s a name for the smell of rain, too: “petrichor,” a poetic portmanteau of the Greek words “petros” (stone) and “ichor” (the blood of the gods in Greek mythology).  Petrichor: the smell of rain. But what causes it? The n…