But moments before a rain event, an “earthy” smell known as petrichor does permeate the air. People call it musky, fresh – generally pleasant. This smell actually comes from the moistening of the ground. ... A byproduct of their activity is an organic compound called geosmin which contributes to the petrichor scent.2 Sep 2018
earthsky.org › earth › what-is-smell-...
Why you can smell rain