Why is it that the air smells so wonderful after a welcome downpour of rain?
Often, when out walking or working in the garden, I have been struck by the wonderful fragrance that comes with a sudden shower of water on dry ground or parched earth. I put it down to the sudden refreshing of foliage or grass blades – but there is a technical, chemical word for it – ‘petrichor’.
This was identified in the 1960s – researchers found that the smell is produced by bacteria in the soil that create a molecule called geosmin. As rain hits the ground geosmin is released into the air. As well as being used in the production of certain antibiotics it is used in commercial perfume production. One perfumier has said ‘It’s a really potent material and it smells just like the concrete when the rain hits it. There’s something very primitive and very primal about the smell.”
Not for nothing does the word petrichor have Greek roots – petros, meaning ‘stone’ and ichor, meaning ‘fluid that flows in the veins of the gods’. The perfume ‘matti ka attar’ has been made in Uttar Pradesh, India for countless years. Petrichor is so potent that the minutest amount is identifiable even when diluted billions of times. It can be blended with essential oils of vetiver, sandalwood, patchouli, jasmine, rose, ylang-ylang, and frankincense.
Often used to freshen the air, as an ingredient in aromatherapy and as a soothing agent in the relief of stress its calming and restorative qualities help focus the mind and impart a sense of well-being.
So next time you are caught out in the rain, pause for a moment and enjoy the extraordinary smell of this amazing phenomenon.