Youngsoo Joung and Cullen R. Buie used high-speed cameras to capture raindrops falling on 28 different types of surfaces and studied what happened to the rain on impact.
Joung and Buie found that when rain hits a porous surface, like soil, tiny champagne-like bubbles of air are trapped and shoot upward, according to a statement from MIT. The researchers contend those bubbles, or aerosols, may release aromatics (i.e. that earthy smell) and possibly other things stored in soil, such as viruses and types of bacteria.
“It’s a very common phenomenon, and it was intriguing to us that no one had observed this mechanism before,” Buie, an assistant professor of mechanical engineering at MIT, said in the statement.
The study may serve as a jumping off point for other research about chemicals in soil and how they “can be delivered in the environment, and possibly to humans,” Joung noted in the release.
Joung and Buie conducted approximately 600 experiments for the study that was published recently in Nature Communications.