What creates the evocative smell of fresh rain when you venture outside following a heavy downpour ?
Finding the origins of rain's aroma was the primary focus of two Australian scientists who in 1964 begun a concerted effort to investigate the phenomenon. In an article entitled "Nature of Agrillaceous Odor", Isabel Joy Bear and R. G. Thomas coined the term "petrichor" to help describe the smell of fresh rain.
It turned out that one of the main sources of the aroma is the blend of oils some plants secrete during dry periods. When the rain arrives, compounds from the oils are mixed and released in to the air along with geosmin, a chemical produced by bacteria in the soil. "It's a very pleasant aroma, sort of a musky smell," said soil specialist Bill Ypsilantis. "You’ll also smell that when you are in your garden and you’re turning over your soil."
"Step outside after the first storm after a dry spell and it invariably hits you: the sweet, fresh, powerfully evocative smell of fresh rain."
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Source: Smithsonian Magazine
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