Candles. Perfumes. Fabric sprays. Laundry detergents.
There are so many products on the market that try to capture the smell of rain. And it’s no wonder: That distinct, earthy odor wafting through the air after a rainstorm is a delightful scent that everyone loves.
Turns out, there’s a reason for that: When the rain hits the ground, it triggers the release of chemicals, which combine with other chemicals to create the aroma. It’s a phenomenon known as petrichor — a term coined in 1964 by a pair of Australian scientists.
According to a 2017 study in Nature, soil-dwelling bacteria known as actinomycetes secrete geosmin (a common compound found in moist, forested areas), when producing spores during arid periods. Those tiny spores are then kicked up into the air by the force of rain hitting the ground, and a pleasant scent is carried by the moist air into our noses.
“It’s sort of a musky smell,” Bill Ypsilantis, a soil condition and health specialist with the U.S. Bureau of Land Management, told NPR in 2007. “You’ll also smell that when you are in your garden and you’re turning over your soil.”
Ypsilantis noted that actinomycetes play a crucial part in the decomposition of organic materials, which feeds soils the nutrients they need.
The rain smell when turning the garden soil, he continued, “is a good indication because that tells you, you have good organic material in the soil. The soil is not too wet. It’s not too dry.”
But science doesn’t only reveal why the smell of rain is so appealing. Studies have also explained why you love certain other fragrances, such as citrus, pine or fresh-cut grass.
Pine trees, for example, produce pinene, an organic compound that belongs to the class of hydrocarbons known as terpenes. The chemical is responsible for pine’s fresh, woodsy odor — or what many people call “the smell of winter” — and spending time in forests, inhaling this scent, has been found to help reduce stress, depression and anxiety, according to research conducted by Japanese scientists in 2007.
There are so many aromas found in nature that are delightful to our noses. And now you know why: It’s science!