If you have been awaiting a downpour from the skies with baited breath and it comes, do you feel like you can actually smell the rain? You can, and this pleasant smell has a name. The powerful, earthy scent produced when rain falls on dry soil is called Petrichor.
Two Australian scientists, Isabel Joy Bear and R. G. Thomas, began the scientific study of rain’s aroma in 1964. They coined the term ‘petrichor’ to help explain the smell we get after rainfall, particularly after very dry spells. The word combines a pair of Greek roots: ‘petra’ meaning stone and ‘ichor’ meaning the blood of gods in ancient myth.
In that study and in the research which followed, they determined that one of the main causes of this distinctive smell is a blend of oils secreted by some plants during dry periods. When a rainstorm comes after a drought, compounds from the oils which have accumulated over time in dry rocks and soil are mixed and released into the air.
The second reaction that creates petrichor occurs when chemicals produced by bacteria in the soils, known as actinomycetes, are released. These aromatic compounds combine to create the pleasant petrichor scent when rain hits the ground.
So next time someone looks at you smelling the air after rainfall, you can tell them that you are not simply a mad gardener, you are breathing in the powerful, earthy scent of petrichor!