What causes that indescribable scent when it first starts to rain?

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What causes that indescribable scent when it first starts to rain?

In: Chemistry

Id imagine its all of the pollen and other ground bound particles being kicked up by the rain drops hitting the ground. Im also curious what causes the scent right before it rains.

I was told it is largely a clay/mineral called Kaolinite. In the distance, where it is raining, the Kaolinite gets wet and releases that distinctive smell that is then carried on the wind for you to smell.

May be untrue, but the college proffessor of minerology that was teaching the class had a sample of Kaolinite and if you wetted it and then smelled it, it was exactly that smell.

It’s called “petrichor”, and it’s a scent that’s created when rain hits dried soil. Plant oils soak into absorbent dirt over time, and are then released into the air when the dirt starts getting wet.

The scent has been isolated and is commercially available as a fragrance material called “geosmin”. The human sense of smell is *ridiculously* sensitive to geosmin, and you can smell it in concentrations as low as just a few parts per *trillion* – one single drop of geosmin in an Olympic-size swimming pool is detectable.