Before you dive down my throat, that’s the way it’s spelled in the title of this Ludovico Einaudi offering.
You and I would spell it Petrichor, wiv an aitch.
Petrichor is the earthy scent produced when rain falls on dry soil. The word is constructed from Greek petra, meaning “stone”, and ichor, the fluid that flows in the veins of the gods in Greek mythology.
Yeah, like that.
But either way, you can hear the rain and smell that scent in this energetic yet beautifully relaxing song:
Petrichor happens (exists?) as the result of a two separate chemical processes triggered by the rain.
Firstly, oils – palmitic acid and stearic acid – secreted by during dry periods, and when it rains, these oils are released into the air. The second reaction that creates petrichor occurs when a chemical called geosmin (you may remember it from such post as Safe To Drink) produced by soil-dwelling bacteria called Actinomycetes is released. Geosmin and these plant oils combine to create the pleasant petrichor scent when rain hits the ground.
Actinos – great to look at under a microscope, absolute bastards to grow in the lab.
Add to those two the “pre-rain” ozone smell you get ahead of storms and you’ve got the most evocative odour outside of cut grass and freshly baked bread.