What’s Up Weather with Jordyn: Why does rain smell?


GREENVILLE, N.C. (WNCT) — Have you ever wondered where the smell of rain comes from?

Like most things that occur in the atmosphere, rain smell is not as simple as it seems. That musky smell you’re thinking about is not from rain. The rain itself does not have a smell. 

This unique smell, known as petrichor, is created by earthy substances released into the air only when the ground gets wet. To understand petrichor formation, we must go all the way back to our first chemistry class and revisit compounds. Now, remember, a chemical compound is a mixture of different elements. So more specifically speaking, petrichor is made up of fragrant chemical compounds. 

The three specific chemical compounds that aid in creating this natural earthy smell includes ozone, geosim, and plant oils. When lightning cuts through the atmosphere, it breaks apart different molecules. After these molecules split, some combine and create ozone. Rainfall itself carries ozone to the surface. 

Then there is also geosim, which comes from bacteria present within soil. It’s released into the air as soon as it rains. The third compound is created by plants. With longer stretches of dry weather, molecules build up in between rocks and within soil. Once the ground is wet from rain, these molecules release plant oils which also add to smell. 

Although all three components are always present, this smell cannot be scented until water soaks into the ground. That’s all for now. Thank you for tuning in, I am meteorologist Jordyn Jenna.

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