Raindrops that move at a slower rate tend to produce more aerosols; this serves as an explanation for why the petrichor is more common after light rains. Actinomycetes is the bacterium responsible for producing spores in soil.

And also 

So plants and mud have a smell just like your ice-cream so when the water droplet touches the mud and makes it wet 

Petrichor (/ˈpɛtrɪkɔːr/) is the earthy scent produced when rain falls on dry soil. The word is constructed from Greek petra (πέτρα), "rock", or petros (πέτρος), "stone", and īchōr (ἰχώρ), the fluid that flows in the veins of the gods in Greek mythology. 

So as you know rain has a distinct smell much like a pleasent and relaxing one so today we are gonna learn and know all about it.

In 2015, scientists from the Massachusetts Institute of Technology (MIT) used high-speed cameras to record how the scent moves into the air. The tests involved approximately 600 experiments on 28 different surfaces, including engineered materials and soil samples. When a raindrop lands on a porou...