Rain does not only fall. It lifts the earth.
When a drop strikes porous soil, it can trap a pocket of air small enough to hide inside the drop. The bubble rises and bursts, throwing an invisible spray upward. These fine aerosols carry compounds made by soil microbes, including geosmin, toward the nose.
Plant oils, ozone, and local conditions also shape the familiar scent; rain has no single smell.
Sometimes what we call the smell of rain is not the sky coming down.
It is the earth entering the air.
What falls from the sky makes the ground rise.