The heavenly perfume of rain after a dry spell is because of a substance referred to as geosmin made by micro organism referred to as Streptomyces dwelling in the soil (Weather Eye, April 19). But the scent can also be referred to as petrichor, as Jane Wolstenholme in Hove fairly rightly identified (Letters, April 20). To add to the confusion, pertichor is used to explain each the perfume of rain and in addition a mixture of chemical substances together with geosmin which are concerned in the musty scent of moist earth.The time period petrichor was coined by the Australian scientists Richard Thomas and Isabel Bear in a pioneering research printed in the journal Nature in 1964. They described the earthy smell from rain after a dry spell and named it petrichor
https://www.thetimes.co.uk/article/how-does-the-smell-of-rain-reach-us-v25d52qht
