Petrichor - The Smell of Rain
First Published on the 20th March 2022
Most Recently Updated on 26th May 2026
“Petrichor - a distinctive, earthy, usually pleasant odor that is associated with rainfall especially when following a warm, dry period and that arises from a combination of volatile plant oils and geosmin released from the soil into the air and by ozone carried by downdrafts”
I love the smell that you get just after a rain storm. I sometimes offer Forest Bathing activities around interacting with the rain, inviting people to notice the rain, the sounds of drops falling, the silence between drops, the feeling of the rain on their skin, and noticing the smells that often follow rain or storms. I was intrigued to know that there is actually a word to describe this smell and that word is ‘Petrichor’.
The phrase ‘Petrichor’ was first used by two Australian researchers, Isabel Joy Bear and Richard Thomas, in a 1964 article published in the journal nature called ‘The Nature of Argillaceous Odour’ to describe the smell of rain when it falls on dry soil. The word comes from the Greek words 'petra', meaning stone, and 'ichor', which in Greek mythology refers to the golden fluid that flows in the veins of the immortals. But petrichor is much more than just a poetic word! It points to a real chemical conversation between rain, soil, plants and micro-organisms.
The researchers found that during dry weather, plants produce and secrete oils that signal seed germination and root growth to stop, and that these oils then accumulate between rocks and combine with chemicals produced by bacteria in the surrounding soil. These bacteria are what gives damp soil its characteristic smell. One of the primary molecules responsible for this is called Geosmin, produced by a bacteria called Streptomyces that is commonly used to create antibiotics. Geosmin is a natural bicyclic terpene with an earthy odour. Terpenes are a kind of phytoncide, the source of the scent emitted by many plants.
How Does Rain Release The Smell?
As the air becomes more humid just before a rain storm, the soil begins to moisten and the speed at which Geosmin is produced increases. When it rains, particularly onto dry, dusty or clay soils, the water droplets spatter, ejecting tiny particles referred to as aerosols. Thes aerosols contain geosmin and related petrichor compounds that are then released into the air and the scent is blown in the wind. Geosmin has a very complex chemical structure that means that it can be registered by the human olfactory system (the mechanism through with we detect and recognise smells) at extremely low levels. It is though that much of humanity has developed in cultures that depend on regular rain fall, and that this may be the reason why so many people enjoy the smell of rain.
Humidity, Lightning and Ozone
The rain following long period of dry weather is often accompanied by thunder storms and lightning caused by rising warm and humid air cooling when it collides with lower temperatures in the upper level of a cloud. Lightning can split molecules of oxygen and nitrogen and rearrange them into nitric oxide (NO) and Ozone (O₃). These ozone molecules are then carried down by droplets of rain, contributing to the particular smell that follows a thunderstorm.
The smell of Petrichor is so appealing that Geosmin has been used in perfumes since the 1960s, although, whilst humans like the smell, many are less keen on the taste of Geosmin, as it is what give beetroot it’s earthy taste!
What makes petrichor so memorable is not only its chemistry, but the way it changes our relationship with the landscape. A rainy woodland path, damp moss, wet bark, leaf litter, and exposed earth all seem to speak more clearly once the rain has passed. In that sense, petrichor is not just a smell; it is an invitation to notice the living system beneath our feet.
Petrichor, Forest Bathing and Nature Connection Practices
This is where petrichor and Forest Bathing meet beautifully. Forest Bathing, or Shinrin-yoku, is a practice of slow, mindful immersion in the forest environment, and research reviews consistently suggest that it can support stress reduction, lower cortisol, reduce sympathetic nervous system activity, and improve mood. The evidence is promising, although reviewers also note that study quality varies and that more robust research is still needed.
In practical terms, Forest Bathing is not about achieving anything. It is about becoming more ‘present’. It asks us to walk more slowly, soften the mind, and allow the senses to lead. Petrichor fits naturally into that approach because scent reaches us in an immediate, wordless way. You do not have to interpret the smell of rain; you simply receive it. In a forest, that can become a doorway into presence. The scent of wet soil, fallen leaves, bark, fern, and moss can gather into a single moment of belonging. This is an inference from the practice itself: when attention is slowed and widened, sensory detail becomes easier to notice and deeper to receive.
There is also something profoundly grounding about petrichor after a dry spell. Dry weather can leave the landscape feeling closed, tense, and dusty. Rain loosens that stillness. It releases scent from the earth and seems to wake the whole place up. For many people, this mirrors the emotional effect of time in nature: a softening of inner weather, a sense of release, a return to rhythm. Again, that connection is interpretive rather than clinical, but it is one that many nature practitioners will recognise immediately.
You might think of petrichor as one of nature’s small acts of welcome. It tells us that the ground is alive, that rain has touched the land, and that the forest floor is still in conversation with the sky. In a forest bathing session, this can become a lovely place to pause: to stand still, breathe slowly, and let the rain-washed air settle around you. The practice does not need to be elaborate. Often the simplest noticing becomes the most nourishing.
A Simple Petrichor Practice
After rain, find a safe place outdoors where you can stand or sit quietly for a few minutes. Slow your walking. Notice the temperature of the air on your face. Breathe gently through your nose and see whether you can detect layers in the scent: wet earth, bark, moss, leaf litter, stone, grass. Let the smell arrive without trying to name it too quickly. Then notice what happens in your body as you stay with it. Does your shoulders soften? Does your breath lengthen? Does the world feel a little closer?
A Closing Reflection
Petrichor reminds us that the earth is never truly silent. Even after a dry spell, life remains waiting just beneath the surface, ready to rise with the rain. Forest bathing gives us a way to meet that moment with attention. Together, they offer a gentle lesson: healing is not always dramatic. Sometimes it arrives as scent in the air, a darkening of the soil, and the simple, unmistakable feeling that the natural world has opened its hand and invited us in.
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