Archive · 12 Jun 2025
Petrichor: The Science Behind the Earthy Rain Smell
Have you ever noticed that special smell after it rains?
It's called petrichor!
It's made up of tiny things like geosmin, made by soil bacteria, and oils from plants.
When rain hits the ground, it releases these into the air, and we can smell them!
Even before the rain, lightning creates ozone which adds to the smell.
Our brains connect this scent with memories and happiness, possibly because smelling rain used to mean we'd find water, helping us survive!
Petrichor is the name for the earthy scent produced after rain, a combination of geosmin and plant oils.
Geosmin, a molecule produced by soil bacteria, is released when rain hits the ground.
Humans are highly sensitive to geosmin, detecting it at extremely low concentrations.
Lightning before a rainstorm creates ozone, which contributes to the pre-rain smell.
Petrichor triggers memories and emotions, potentially linked to survival and the availability of water.
- Who
- The scent is produced by soil bacteria called Streptomyces, and plant oils, and is detected by humans.
- What
- Petrichor is the name of the earthy scent after rain, caused by geosmin and plant oils.
- When
- The scent is most noticeable immediately after rainfall.
- Where
- The scent is present where rain falls, influenced by local environments.
- Why
- It is the release of geosmin and plant oils into the air after rain, creating a sensory experience linked to memory and possibly survival.
- Name
- Petrichor
- Origin
- Greek: petra (stone) and ichor (blood of the gods)
- Main Component
- Geosmin
- Produced By
- Soil-dwelling bacteria called Streptomyces
- Sensitivity
- Humans can detect geosmin at 5 parts per trillion
- Pre-Rain Smell
- Ozone produced by lightning