Each thing has its own smell. There is the fragrance of flowers, there is the fragrance of food, there is also the stench of rotten things. Similarly, after a downpour, a very familiar scent is found. Some people call it smell. The smell before the rain and the smell after is different. Some organic compounds are responsible for this. There are three main sources. Bacteria in the soil, soil, oil emitted from plants and electron charge emitted during lightning.
Let's talk about bacteria, their name is actinomycetes. They make a kind of organic compound called geosmin. It is hidden in the ground. Later it mixes with rain water. Then it comes in contact with air and then a special kind of scent is found. Very few geosmins are enough to create the smell of rain. Only 5 percent geosmin per trillion. If there is 1 teaspoon of geosmin in the water of 200 swimming pools, we will get the smell.
A type of oil made from trees is also responsible for this smell of rain. Studies have shown that in the dry season, trees produce a mixture of oils. This oil reduces water demand by inhibiting plant growth. The tree collects this oil mixture from the soil and rocks. Later the volatile substances in it are mixed with rain water and released into the air. The mixture of these oils mixed with geosmin creates a special scent. In 1974, scientists named it the petrichor.
Even before the rain starts, a kind of scent is found. This scent is found during frequent lightning strikes. Its source is the electric charge present in the atmosphere. Lightning breaks down the oxygen molecules present in the air and converts them into oxygen atoms (pictured left). That free oxygen combines with other oxygen molecules to form the ozone molecule (O3). And ozone has a strong odor, much like chlorine or burnt wire. It is usually found in the upper layers of the atmosphere. But any downward storm carries this scent to the bottom. And then we get that sweet smell.
