Weatherz School: The smell of rain

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There’s something nostalgic about a rainy day. Perhaps it’s because the wet weather hits home with all of our senses.

You can listen to the rain against the window. You can watch the splashes in the puddles. If you’re caught in the rain, you certainly feel it.

You can even taste it if you want, but don’t expect the raindrops to turn to candy canes and gumdrops. And yes, rain even comes with a smell.

The smell of rain can actually be one of three things. Soil-dwelling bacteria secrete “geosmin” when producing spores. Raindrops help release this earthly-smelling chemical into the air.

Plants are another source of smell. They secrete oils during dry periods. When it rains, compounds are released from those oils that give off an odor. This is called “petrichor.”

The third thing we smell isn’t from the rain, but from the lightning that comes with thunderstorms. Lightning can split oxygen molecules into individual atoms. Those atoms combine with O2 molecules to make O3, which is ozone. This has a distinct odor that can form ahead of the storm preceding the rain.

So the next time wet weather brings a surge to your senses, you’ll know where it’s coming from.