Dear Tom,
I can sometimes actually smell rain, but friends say I am crazy. What do you think?
Tommy Rosen

Dear Tommy,
The smell associated with rain is not in your imagination. “Petrichor” is the name given to the phenomenon associated with the smell of rain. In studies conducted at the Massachusetts Institute of Technology, it was found that raindrops cause aerosols to be released into the air. High speed cameras were used to record what happens when raindrops hit a porous surface. The raindrops first start to flatten and tiny bubbles of air are trapped at the point of contact. The bubbles than shoot upward, bursting from the drop in a fizz of aerosols. The aerosols, released during light or moderate rains, not so much during heavy rains, account for the familiar smell of rain.