On this rainy Friday, I want to highlight a recent study which was published in Nature Communications. From Wikipedia:
Petrichor (/ˈpɛtrɨkɔər/) is the earthy scent produced when rain falls on dry soil. The word is constructed from Greek, petra, meaning ‘stone’ + ichor, the fluid that flows in the veins of the gods in Greek mythology. The term was coined in 1964 by two Australian researchers, I. J. Bear and R. G. Thomas…
Scientists have recently discovered what makes the smell of rain so pleasant. Andrew Freedman described the study in his Mashable blog at http://mashable.com/2015/01/14/study-identifies-rain-smell/. According to the study, which used high-speed photography, when raindrops hit the ground, they eject aerosols or tiny particles from the soil, shooting them into the air at high speeds and adding a scent to the air. The technical term for this is “frenetic bubble generation.” It works best when the rain is not too heavy. Some soils are more amenable to producing the smell of rain than others.
You can see video of this process at Mashable and at http://phys.org/news/2015-01-high-speed-imaging-captures-raindrops-clouds.html.