Petrichor
After rainfall, the distinctive aroma is released from the soil.
Despite being an unwelcome form of weather by many, rain is an essential event for sustaining life on Earth. Communities throughout history have always welcomed rainfall as an aid to their growing crops – and scientists think it’s for this reason that so many still enjoy the smell that follows the rain. This is called petrichor.
The raindrops themselves aren’t responsible for the scent that fills the air after it starts to rain. Rather, the water droplets cause various fragrant compounds to be released from the soil. As raindrops scatter over dry earth, the water traps tiny bubbles of air at the ground’s surface. These droplets then splatter, bursting the bubbles from the loose soil and carrying plant oils and other natural chemicals upwards into the air in an aerosol form.
STORMY SCENT
Rain isn’t the only weather event that’s responsible for natural and distinctive smells. Thunderstorms produce a different scent that’s caused by a disturbance in the atmosphere. When lightning strikes through the atmosphere, nitrogen and oxygen molecules split and combine with each other to form nitric oxide and single oxygen atoms.
These oxygen atoms then react with oxygen molecules in the air, making ozone (O3). Ozone is a less stable molecule compared to oxygen’s elemental form (O2). During a storm, air sinks to form downdrafts and pushes ozone lower into the atmosphere where we can smell it. It has a metallic scent, which makes it possible to identify when rain is soon to fall.
