It is a hot summers night. The air is humid, crickets are chirping and you can hear the gentle rumble of a thunderstorm off in the far distance all of a sudden an earthy smell wafts into your nostrils and instantly you know it is going to rain. We are all familiar with this smell, but why is this? Well, the answer is stranger than you might think and Morecast has the details.
The scent of rain or Petrichor by its scientific name is actually a mixture of ozone, oil extruded by plants and a bacterial by-product known as geosmin.
How does this all occur?
As a thunderstorm approaches lightning causes oxygen molecules to split apart and recombine with other oxygen atoms to form ozone. The turbulent nature of a thunderstorm causes ozone to blow down to ground level and ultimately your nose. Secondly, as rain hits the ground a bacterial by-product known as geosmin, is stirred up from the ground along with oils produced from plant matter during dry periods. All of these processes are thought to lead to the distinct scent of rain and explains why the scent of rain is stronger during prolonged drier periods.
Why does rain smell so good?
Many scientists think that over the course of human history we have evolved to detect the smell of Petrichor due to our reliance on rain for survival. Further to this, the Neolithic shift from hunter-gathering to agriculture also enhanced our need for rain and thus became further ingrained into the psyche of many cultures throughout the world.