Where Does the Smell of Rain Come From

Where Does The Smell of Rain Come From?

inidevan com You know that amazing smell that hits you right when the first drops of rain start to fall? It’s got a name—petrichor—and the science behind it is seriously cool. Joe Hansen from It’s Okay To Be Smart breaks it all down.

Our noses are super powerful—they can pick up as many as a trillion different scents. And some of those smells stick with us in ways that are deeply personal, like the scent of your grandma’s house or that old teddy bear you used to sleep with. But there are also scents that almost everyone connects with. The smell of rain is one of them. You’d be hard-pressed to find someone who doesn’t feel something emotional when they catch that earthy aroma.

rainstorm petrichor earthy smell

So where does that smell come from? According to Joe Hansen, there are three main chemical sources. The first one is ozone. Yep, that’s the same stuff that gives the air a sharp, clean smell after a lightning storm. The word “ozone” actually comes from the Greek word for “to smell.” When lightning strikes, it splits oxygen molecules into atoms, and some of those atoms recombine into ozone. That ozone gets carried down by the winds before a storm and ends up right in your nose.

lightning storm ozone formation

But once the rain actually starts falling, the smell changes. That’s when petrichor kicks in. The name comes from Greek roots—“ichor,” which was thought to be the magical fluid that flowed through the gods’ veins, and “petros,” meaning “stone.” So basically, it’s like the “god’s blood” of the Earth. The science here is pretty wild too. When rain hits dry soil, it stirs up decomposed organic material that’s been sitting on the ground. Some of that stuff gets picked up by the wind and lands on rocks, mixing with minerals. Then, when the raindrops hit, they release this whole mix into the air, creating that unmistakable, earthy scent.

rain hitting dry soil petrichor release