It's the season for smells and aromas...

Read Martin's column every week in the Western Morning News

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HERE have been numerous opportunities to sniff the unique and unmistakable smell of petrichor recently. It’s that curious aroma you can detect when rain has fallen on warm, dry ground. The smell you sniff in spring or summer after a quick rain or thunderstorm puts an end to a period of sunshine and heat.

There was a lot of petrichor around at the start of the week as the rainstorms came and went.

The term was coined by two Australian science agency researchers in a 1964 article for the journal Nature. Their studies led them to discover that rocks which had been exposed to warm, dry conditions were “steam-distilled”.

This revealed a yellow coloured oil that had become trapped in rocks and soil - and it’s this substance which creates the smell. The original source of this yellow stuff comes from a combination of oils secreted by plants during dry weather, as well as chemicals released by soil-dwelling bacteria. When high humidity occurs as a precursor to rain, the pores of rocks and soil become trapped with moisture, forcing some of these oils to be released into the air. Dusty soils trap tiny air bubbles on the surface, which then shoot upward when heavy raindrops hit. A bit like bubbles rising from a glass of champagne. The bubbles then burst, throwing aerosols of scent into the air where they are then distributed by wind.

So now we know... That curious, earthy, rather bitter, summer rain smell has its very own name for good reason.