After the rain, breathe in the Earth’s lifeblood
In between the recent downpours of the past few days I have bolted out the back door to pace around my garden like a prisoner in the exercise yard. As I have done so I have considered the same recurrent thought – why does it smell so glorious after the rain?
That peculiar scent of freshly fallen rain after a long dry spell is as intoxicating the world over. The notes are different, of course, but powerful enough to transport me in an instant from Sheffield suburban garden to east African dirt road to South American rainforest and back again.
The smell is known as “petrichor”, coined by Australian researchers Isabel Joy Bear and Richard Thomas in their 1964 article Nature of Argillaceous Odour, published in the journal Nature. The word derives from the Greek petros, meaning “stone”, and ichor, meaning “the fluid that flows in the veins of the gods”.
A key component of petrichor is an organic compound called geosmin which lingers in moist soil. The compound is what gives the flavour to many root vegetables and is used in perfume, too. Drops of water hitting the Earth cause geosmin to be released into the air.
It seems humans are not the only ones attracted by the scent. Some interesting research has been done recently on the beneficial relationship between the bacteria which make up geosmins and insects called springtails.
The study discovered the insects were attracted to eat the spores and in turn help spread them around.
There is forecast to be plenty more rain around this weekend, in between brighter spells. Ample opportunity, in other words, to make the most of that golden moment when the clouds have lifted to breathe in deep the scent of the life blood of the Earth and contemplate the ancient movements occurring beneath our feet.