04/25/2022
Since the rain, rain isn't going away we might as well use it as an opportunity to learn something new. 🌧️
April showers not only bring May flowers, but also produce petrichor. What is petrichor? It’s the unique and fresh smell associated with rain.
Geosmin, plant oil secretion, and even lightning can play a role in that earthy fragrance we smell after a thunderstorm.
Geosmin is a compound created by Actinomycetes bacteria. This bacteria is present in most healthy soils. When rain droplets hit the ground, geosmin is released into the air. Geosmin in the air can be detected by the human nose at less than 5 parts per trillion!
Plants produce oils that accumulate in between rocks and in soil. When it rains, these compounds are released, further contributing to petrichor.
Thunderstorms also play a role in petrichor. When lightning strikes high in the atmosphere oxygen and nitrogen molecules are split, and create ozone (O3). Ozone, which has an obvious aroma, similar to that of chlorine, is then carried down by the rain.
Rain also helps clear the air of dust particles and aerosols, effectively cleaning the air and making the earthy smell more potent.
Photo: Rain drops fall into large puddles at Cannon River Trout Lily SNA.
mndnr.gov/snas/sna01002
