The smell of a new book. Freshly baked bread. And the fresh smell of rain. Why do most people find these smells so tempting? Why does it smell so good when it rains?
There are few explanations as to why certain unusual smells are so pleasant to our brains. Especially when it's raining. And they finally figured out how to do it miraculous aroma produces.
The pleasant, fresh smell is the result of an organic compound geosmin (whose name is also derived from the Greek words for "earth" and "smell"), produced by bacteria Streptomyces, when they die. The human nose is sensitive to geosmin and can also detect it in the concentrations, which are low (five parts per billion).
In 2017, a group of mechanical engineers using high-speed cameras and fluorescent dye recorded water droplets, which fell on different soil types, therefore raindrops. When the raindrops hit the ground at the right speed, they air bubbles trapped under them. During the journey of the bubbles to the surface, they ejected hundreds of small droplets containing geosmin and bacteria into the air. The bacteria survive in a small droplet for about an hour, then travel on the wind.
— Dave Fawbert (@DaveFawbert) July 30, 2018
Sometimes these airborne bacteria can be harmful due to the transmission of many viral and potentially fatal diseases (e.g. melioidosis, which spreads during the rainy season in Southeast Asia and northern Australia), which explains, among other things, the connection between rain and many diseases, which are transmitted by droplets traveling through the air.
More information:
nature.com
