Petrichor is the earthy scent released when rain falls on dry soil.

The word was coined in 1964 by two Australian scientists, who blended the Greek words for stone (petra) and the fluid that flows through the veins of gods (ichor).

The smell comes from a compound called geosmin, released by soil bacteria, along with oils that plants secrete during drought as a survival mechanism. These substances become trapped in rock and soil and are released into the air when rain hits the ground.

Humans tend to find the scent pleasant partly because rain was essential for the survival of our ancestors, so your brain may be responding with a very ancient, almost primal emotional reaction every time a storm rolls in.