One of these odors, called “petrichor,” lingers when rain falls after a prolonged dry spell. Petrichor — the term was coined in 1964 by two Australian scientists studying the smells of wet weather — is derived from a pair of chemical reactions.
These oils collect in the soil and in rocks; rain then causes a range of smaller, volatile compounds within them to be released into the air. Their combination with geosmin in the air causes ‘petrichor’ – the name given by scientists in 1964 to the smell after rain.
Another after the rain smell comes from volatile oils that plants and trees release. The oil then collects on surfaces such as rocks.