Before a rainstorm, a thunderstorm’s downdrafts bring ozone from higher altitudes to a level where humans can smell it.
The result is a sweet smell, indicative of an incoming storm.
During the period of time that it’s dry before a storm, plant’s secret oils that accumulate in dry dirt and rocks.
When rain falls, the oil is mixed and released resulting in quintessential smell of rain, also known as Petrichor.
After a storm, bacteria are sent into the air, which result in an earthly smell known as Geosmin.
While humans don’t have an innate response to the odor of the rain, research has shown that aboriginal people of Australia link the odor of rain to the color green, and it helps them catch game, like Kangaroo and emu. Researchers call this a sort of ‘cultural synesthesia’
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