Why does rain sometimes have a "smell"? - WMC Action News 5 - Memphis, Tennessee

Why does rain sometimes have a "smell"?

Have you ever noticed that smell just before or at the beginning of a shower or good soaking rain? I love that smell. But I don’t smell it before every rain event.

Sometimes, it’s very strong and sometimes you don’t smell it at all. Researchers may have figured out how that smell occurs and they even have a name for it. The smell of rain is referred to as Petrichor.

The higher moisture content and humidity before a rain gets trapped in the pores of rocks and soil forcing some of the oils to be released into the air.

But the strongest smell is released when rainfall arrives. Raindrops landing on dusty or clay soils, they trap tiny air bubbles on the surface which then shoot upward - as in a glass of Champagne - and burst out of the drop throwing aerosols of scent into the air where they are then distributed by wind.

The scent is most noticeable when light/moderate rain falls on sandy or clay soils. During heavy rain, the speed of the drops keep bubbles from forming which reduces the aerosols. You can see a cool video of this process and more details about this phenomenon on the link below.  

http://www.metoffice.gov.uk/learning/rain/petrichor

Spencer Denton
WMC Action News 5 Morning Meteorologist
First Alert Storm Tracking Team
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Meteorologist Spencer Denton
Twitter: @sdentonwx

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