The scent is caused by a complex interaction between several factors, including the release of volatile compounds from plants and soil, and the physical process of raindrops hitting the ground.
When it hasn't rained for a while, certain plants and microorganisms release a mixture of oils, acids, and other chemicals into the soil. When rain falls, it disturbs these compounds and they are released into the air as aerosols, which can travel far from their source. Some of the compounds that contribute to the smell of rain include geosmin, a molecule produced by certain types of bacteria, and various terpenes, which are produced by plants.
Another factor that contributes to the smell of rain is the physical process of raindrops hitting the ground. When raindrops hit a porous surface, such as soil or pavement, they can create tiny air bubbles that contain some of the aerosols mentioned above. These bubbles then burst and release the aerosols into the air, contributing to the scent of petrichor.
The scent of rain can also vary depending on location and weather conditions. For example, in urban areas, the smell of rain may be influenced by pollution or other contaminants in the air. Additionally, the scent of rain may be stronger in areas with higher levels of humidity, as this tends to increase the release of aerosols from the soil.
Whether you care to know the science behind the smell or not, one thing is for sure: Rain is a natural wonder, a necessity to our planets survival, and a subject of endless human wonder...
