So twin you're probably familiar with the smell of rain, but do you know what causes it? The scent is known as petrichor, which I'm sure you guys already know it. The term first coined by two Australian researchers in 1964. So the familiar earthy aroma actually comes from soil bacteria, primarily a genus called Streptomyces. When it hasn't rained for a long time, the soil dries out and these bacteria produce spores to survive the dry spell. As they do, they synthesize a chemical compound called geosmin, which is a type of alcohol molecule with an extraordinarily potent scent that humans can detect even at extremely low concentrations. And when rainfall hits the dry earth, those tiny air bubbles get trapped under the raindrops, rise to the surface, and burst anyway. This process kicks the geosmin and bacterial spores up into the air as an aerosol and spreading the distinct scent through the moisture. And interestingly, geosmin can also occasionally contaminate tap water, mineral water, or wine that give them earthy taste that many people find off-putting. That's all a funfact for today twin #BookShare