Can you explain why the air has such a unique fragrance after a rainstorm?
Margaret Robertson, Chicago
A single explanation for the “smell” of rain is lacking. Wet vegetation appears to be partially responsible along with the reaction between moisture and volatile substances on leafy plants. Pine forests release terpenes (substances found in perfumes)into the air. Olfactory specialists believe the moisture, warmth and falling air pressure that often accompany rain, not only enhance our sensitivity to odors, but also hasten the release of fragrant molecules from plants. Petrichor is the name for smell released during a rain. As the flattening raindrops strike the surface, bubbles of air are trapped. The bubbles shoot upward, bursting from the drop in a fizz of aerosols accounting for the familiar “smell of rain.