Book 7, Question 11
Why Does Rain Smell So Good After a Dry Spell?
That fresh smell after rain is called petrichor. It comes from oils made by plants and tiny living things in the soil. When raindrops hit dry ground, they puff those scents into the air for you to smell.
From the book
Page from A Million Whys Book 7
More fun facts
- The word petrichor was first used in 1964 by two researchers at an Australian science agency.
- Plants release oily molecules called fatty acids, which break down into small molecules we can smell.
- Soil bacteria make a chemical called geosmin, a big part of the smell of rain.
- In warm, dry weather, some plants release oils into the soil that stop other seeds from sprouting.
- When raindrops hit the soil, they trap tiny air bubbles that rise and burst, spraying the smell into the air as a fine mist.
- Petrichor doesn't really smell until it rains.
Sources: Science News Explores, BBC
Questions kids ask
What makes the smell of rain?
Oils from plants and a chemical called geosmin made by soil bacteria, carried into the air by raindrops.
Who named petrichor?
Two researchers at an Australian science agency, in 1964.