What's the term used to describe the fresh earthy smell after it rains?
And the answer: petrichor.
When rain falls on dry soil, a fresh earthy scent called petrichor is produced by bacteria in the dirt. The word comes from two Greek words: one for rock or stone, and another from Greek mythology that describes the fluid that flows through the veins of the gods.
Petrichor is the result of more than just rain hitting the earth – it's actually a form of reaction. When a raindrop lands on a porous surface, air from the pores forms small bubbles, which float to the surface and release aerosols. Such aerosols carry the scent, as well as bacteria and viruses from the soil. Raindrops that move at a slower rate tend to produce more aerosols, which serves as an explanation for why the petrichor is more common after light rains.
The molecule that produces smell, geosmin, is present in most healthy soils and is a bacteria also used to create commercial antibiotics. Human beings are extremely sensitive to it, and while we commonly enjoy the smell, the particular taste (found in vegetables like beets) is commonly disliked. Scientists continue to puzzle over this phenomenon, but more likely than not we may thank our innate human inclination toward nature for the pleasant sensation of musky, rainy earth.
Check out the video below to learn more.