The scent begins on the ground
Petrichor is the characteristic smell when rain falls on previously dry ground. Plant oils and substances produced by soil bacteria contribute to it. The smell does not simply belong to the water itself.
Evidence / further reading: Met Office · Rain ↗
Drops can carry substances
MIT researchers observed in the laboratory that raindrops on porous surfaces can trap tiny air bubbles. When these burst, fine droplets enter the air. This offers a possible transport mechanism for substances from the ground; not every shower smells alike.
Evidence / further reading: MIT · Rainfall Can Release Aerosols ↗
Sources & further reading
Facts and basic guidance draw on the sources below. Observation exercises and reflections are our own invitations.
