Even Wonder Why Rain Has The Smell It Does?
Researchers think they now know why rain gives off the odor it does. It turns out raindrops release little bursts of aerosols, or fine particles of liquid suspended in gas. The aerosols given off when rain hits the ground may be sending out signature smells. These smells, in turn, get carried by the wind. This process is called petrichor.
Interestingly enough, it's been proven heavy rain actually produces fewer aerosols than a light or medium rainfall. And when the physics of a raindrop hitting a porous surface, like wet soil, are just right, it could even release a frenzy of aromatic plant oils and bacteria sitting in the dirt. This might even explain how soil microbes spread from place to place.