What causes smell after or before rain ?

What causes smell after or before rain ?

Science has an excellent explanation for this phenomenon, known as its Petrichor. Petrichor is a long odour. We can smell it after it rains or before . There are two  reasons for this smell. That is : -

1. Plant oils: - It is produced by plants. In the summer, the water in the ground is reduced or decreased, so the plants have to compete with one another for water, and in order to do so, they expel the plant oil, such as the substance collected in the soil surface.

2. Geosmin: - The soil contains some bacteria and after the rains those bacteria die. So before they die they give a compound called Geosmin. When it rains, geosmin and plant oil are released into the air and blended to form petrichor. Petrichor is the smell that we breathe when the rain is falling  . 

These are the two reasons for the smell after raining or before raining.