“We can smell different things both before, during, and after it rains,” researcher Anja Røyne says.
And there are interesting reasons for that.
“Before it rains, we humans can sense the smell of ozone. Especially if there are thunderstorms and lightning first,” she says.
When you hear ozone, you might think of the ozone layer far above the Earth.
It works a bit like the Earth’s sunscreen and protects us humans from strong rays from the sun.
But there is ozone in the air we live in as well. And when lightning strikes, there’s more of it.
“Lightning is so powerful that atoms in the air are torn apart and swirl around. When they collide again, ozone can form,” she says.
And that’s what we can smell.
The smell after rain comes from bacteria in the ground.
They produce a scent called geosmin. They do this all the time, but when it rains, they spread into the air.
“You might wonder why the bacteria in the soil bother to produce so much of that substance,” she says.
Researchers have studied this.
“It turns out that geosmin helps the bacteria attract other animals. Especially springtails,” she says.
