Australian scientists Isabel Joy Beer and R.G. Thomas were the first to introduce the term in 1964. Petrichor is derived from the Greek words “petra,” meaning “stone,” and “ichor,” a reference to the flood of gods in ancient mythology. The scent is a mixture of plant oils and a bacterial compound called geosmin, both of which build up when kept dry for too long. Then when it rains again, the power of the raindrops releases this aromatic cocktail into the air right up to our noses. What also enhances this effect is the fact that our noses are extremely sensitive to geosmin.
But maybe you also notice a pungent odor before a drop drops from the sky? Then you might smell ozone, a molecule made up of three oxygen atoms bonded together. It is sometimes found in the air before or after a thunderstorm. The electric charge of a lightning bolt is capable of splitting oxygen and nitrogen molecules in the atmosphere. These then form nitric oxide (NO), which in turn can lead to ozone. A thunderstorm carries this ozone from the clouds up to your nose.
So be sure to run outside at the start of the shower to catch this weather phenomenon.
