Key Takeaways on the Smell of Rain:The smell of rain is known as petrichor, a term derived from petro — meaning rock — and ichor — meaning tenuous essence. But before the rain begins, something happens that delights even people who aren’t so enchanted with rain itself. What Is the Smell of Rain Called? The smell of rain is known as petrichor. What Causes the Smell of RainMore prosaically, but no less fascinating, the scent of petrichor comes from a chemical compound called geosmin.