You know that certain smell in the air after a light rain? Scientists at MIT believe they may have identified the mechanism that releases this aroma, as well as other aerosols, into the environment.
The researchers used high-speed cameras to capture raindrops falling on 28 different types of surfaces and studied what happened to the raindrops on impact.
They observed that when a raindrop hits a surface, it traps tiny air bubbles at the point of contact. As in a glass of champagne, the bubbles then shoot upward, ultimately bursting from the drop in a fizz of aerosols.
The researchers suspect that in natural environments, aerosols may carry aromatic elements (this is, smells), perhaps along with bacteria and viruses stored in soil. These aerosols may be released during light or moderate rainfall, and then spread via gusts of wind.
The researchers results appear this month (January, 2015) in the journal Nature Communications.
Bottom line: High-speed imaging captures raindrops releasing clouds of aerosols on impact.