As the spring showers hit our region, they brought with them more than just rain. They also brought a unique scent that has become synonymous with the season – petrichor. Coined by Australian scientists in 1964, petrichor is a term used to describe the smell produced by rain. It’s not a substance in itself, but rather a combination of chemical compounds released by or contained within the rain that interact to create the recognizable scent we associate with it.
One of the main compounds that contribute to the scent of petrichor is ozone. Rain can absorb ozone molecules as it falls through the air, bringing them down to the ground. Lightning during a rain event can also produce more ozone as it impacts oxygen molecules in the atmosphere. Geosmin, a chemical produced by bacteria in the soil called Actinomycetes, is also released into the air by falling raindrops and can be detected by the human nose at very low concentrations.
Plants also play a role in creating petrichor’s complex chemical stew. During dry conditions, plants produce compounds that accumulate in the soil until rain falls. When this happens, it pushes out these compounds into the air, including stearic and palmitic acid. The scent of petrichor is further enhanced as rain clears dust particles and aerosols from
