From: Peter Hodges 29/05/99 16:34:58 Subject: Smell of Rain post id: 14544 Could you please tell me the gases invlolved in the exchange of gases between the water and soil that causes a smell when it rains and how this process happens. From: Todd Collins 29/05/99 17:08:00 Subject: re: Smell of Rain post id: 14545 The smell of wet soil is produced by a few species of bacteria which live in the soil. They divide at a faster rate (and hence their numbers in the soil increase) when there is more water available to them in the soil, so the smell is more noticeable just after it rains. Sorry, but I can't recall what bacteria are responsible for the smell, and I don't know what the smell chemicals they produce are called. Perhaps someone else here knows... From: steve 29/05/99 18:06:14 Subject: re: Smell of Rain post id: 14553 The smell of rain is a gas called petrichor. The trees and plants give off volatile oils and these are absorbed by the rocks and earth. When it rains, these oils are released again and the gas they produce is called petrichor. The same oils are responsible for the haze that gives the Blue Mountains their name. For further info, check out an early issue of the CSIRO magazine Ecos, issue number 4, I think, but I'll check it for u at work. From: Sue 31/05/99 11:52:49 Subject: re: Smell of Rain post id: 14796 Microorganisms called actinomycetes produce geosmin, which has an earthy smell. The topic "Smell of Rain" has come up previously, use your Edit/Find tool to track down the last thread of this name for more information. This forum is un-moderated. The views and opinions expressed are those of the individual poster and not the ABC. The ABC reserves the right to remove offensive or inappropriate messages.