The Washington Post reports that MIT researchers have discovered that when raindrops hits the ground, aerosols, or fine particles of liquid suspended in gas, release distinct smells.
This phenomenon is called petrichor. A heavy rainfall produces less petrichor than a light or medium rainfall.
Researchers used high-speed cameras to capture raindrops in slow motion. This finding may explain why soil microbes move from location to location.
Via: The Washington Post > Slow-mo video of raindrops reveals how rain gets its distinctive smell