Petrichor

 

Petrichor

This word was unknown to me until I saw it twice in one day, courtesy first of Steve and then of Meike. It is a simple word to describe the almost indefinable scent that accompanies the first rain after a dry spell.

Petrichor is a word that was created in 1964 by two Australian scientists to replace ‘argillaceous odour’ as a description for the wonderful, earthy smell that follows rain. The word derives from a combination of the Greek words petra for stone and ichor, the golden blood of the immortals in Greek mythology. (In medicine, ichor was an archaic word for a thin, sometimes foul-smelling discharge from a wound.)

Bacteria in the soil create a chemical called geosmin, which accumulates in dry weather. At the same time, in the same conditions, soil absorbs chemicals secreted by plants. When rain falls, air in the soil forms small bubbles that rise to the surface and discharge fine vapours or aerosols.

 Humans are highly sensitive to geosmin and detect it even in small amounts. Scientists believe it is possible that ancient humans used this smell to find water and living plants during extreme dry weather, and that geosmin slowed the germination of seeds and subsequent plant growth.

Another word I discovered was ‘pluviophile,’ meaning a lover of rain and someone who experiences delight and serenity on rainy days. There must surely be another word to describe those who eventually tire of endless rain. I found there are two (at least!) – ombrophobia and pluviophobia, but I think there will be a short hiatus before any of us in UK fall prey to that condition.