Light to moderate rains releases fizz of clouds from the soil and make aerosols, bacteria, and viruses airborne. If aggravated by strong winds, these potentially harmful elements can reach far and wide.
The funny smell being released during light rains are actually aerosols trapped as tiny bubbles when droplets hit porous surfaces. These trapped aerosols serve as carriers for bacteria and viruses. The volume of aerosols released depend on the velocity of raindrops and how porous surfaces are.
According to assistant professor Cullen Buie of Massachusetts Institute of Technology, it is intriguing that nobody observed the phenomenon scientifically since rains are a common natural phenomenon. In fact, it is raining right now anywhere in the globe.
Meanwhile, a post-doctoral colleague of Buie, Youngsoo Joung explained that the discovery can explain how some soil-based diseases are spreading. Raindrop-induced aerosols are good starting point for future studies about microbes and chemicals that exist on soils. Further, it can shed light on how certain diseases can be averted.
University journal MIT News discussed how Buie and Joung used 16 soil samples of different permeability to conduct their experiment. Then they used high-speed cameras to capture the simulated raindrops upon impact. What the duo found out is a mechanism that causes air bubbles to be captured simultaneously as the raindrops hit the surface. Much like in champagne, these bubbles rise and explode into tinier particles. Add winds into the equation and they can travel through the air.
There is a higher tendency for bacteria and viruses to get airborne on instances of light rains while heavy rains shorten the distance of their travel. These experiments further illuminated the mystery behind what people call as petrichor, according to Science Daily. First studied by Australian scientist Richard Thomas, petrichor is basically the weird aroma that people smell during light rains.
Scientist believed that petrichor is a product of chemical reaction from plants oils upon rain impact. Scientists also thought that they are certain chemicals that bacteria release but little did they know that they are actually "the bacteria" until the MIT experiment.
