Why Rain Gives Off That Fresh, Earthy Smell   Live Science - January 22, 2015
Walk through the first rainstorm of the season and it slowly hits you: that fresh, earthy smell. Before it hits the ground, rain is just water. It has no smell. But after the drops hit the ground and interact with dirt, the fresh and almost sweet fragrance of rain is let go. Now, scientists think they've identified the exact mechanism that releases this aroma into the environment. The smell actually has a name. It's called "petrichor," from the Greek words "petra," meaning "stone," and "ichor," which refers to the fluid that flows like blood in the veins of the gods. The phenomenon was first characterized (as the familiar smell after a light rain) by two Australian scientists in 1964, but until now, researchers didn't understand the physical mechanism behind it.

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