Listening for Rain: Microbes, Memories, and Summer Storms
- Heather McSharry, PhD
- 3 days ago
- 5 min read
Summary
You can smell rain, sometimes before it arrives. But why?
In this immersive episode of Infectious Dose, we follow a summer storm from distant rain clouds to the microbes beneath our feet. Along the way, we explore petrichor, geosmin, and the fascinating science behind one of nature's most recognizable scents.
But this episode is also about something more personal: the places, memories, and moments that storms seem to carry with them. From watching rain approach across wheat fields in central Washington to listening for thunderstorms on the Gulf Coast, this is a journey through both the science of summer rain and the memories it leaves behind.
Part of our June series, Stories of Summer Rain.
Listen here or scroll down to read episode overview or download full transcript.
Episode Overview
This episode is different. It's not meant to be read. It's meant to be experienced. If you can, listen with headphones.
Before the first drop falls, something changes. The air shifts. The wind rises. And somehow, long before the storm arrives, you already know it's coming.
In this immersive episode of Infectious Dose, we follow a summer storm from distant rain clouds to the microbes beneath our feet. Along the way, we'll explore petrichor, the scent of rain, the soil bacteria that help create it, and the surprising connection between smell, memory, and place.
I adore rainstorms, so this episode is also something else. It's a journey through the storms that shaped my own life—from watching rain approach across wheat fields in central Washington to listening for thunderstorms on the Gulf Coast.
This episode isn't just about the science of rain. It's about what rain means to us.
Put on your headphones.
And wait for the storm.
What you're about to hear
In this episode, we're following a storm as it approaches. You'll begin in central Washington, watching rain move across distant farmland. You'll move through the science of petrichor and geosmin, exploring the microbes and chemistry that create one of nature's most recognizable scents. And eventually, you'll step out onto a patio during a real Texas thunderstorm, listening as rain arrives overhead. The rainstorm we experience when I go out to my patio is a storm recorded in real time. The windchimes, cicadas, birds, and rain are all real sounds from my patio during the storm.
What to listen for
The storm before the storm
Notice how often the episode lingers in the moments before rain arrives. The scent appears before the first drop falls. The wind changes. The atmosphere shifts. Much of what we experience during a storm begins long before the rain itself.
The hidden world beneath your feet
The smell of rain doesn't come from the storm. It comes from the ground. Listen for the moment the story shifts from weather to microbiology and the realization that one of the most beloved scents on Earth is partly the work of soil-dwelling microbes.
The changing soundscape
The episode moves between places and times. Washington wheat fields. Gulf Coast thunderstorms. Indoor spaces. Outdoor spaces. Listen for how those environments change and how different storms carry different memories.
The sounds we stop hearing
One of the themes running quietly beneath the episode is attention. Listen for the moments when familiar sounds fade into the background—and what happens when we begin noticing them again.
Why this episode exists
June's theme on Infectious Dose is Stories of Summer Rain. We've explored hurricanes, mosquitoes, ticks, and the ecosystems that emerge in warm, wet environments. But before moving on, I wanted to spend time with the thing that connects them all: rain itself. Rain shapes ecosystems. It influences infectious disease risk. It changes landscapes. It alters the behavior of animals, insects, and microbes. But rain also shapes memory.
For many of us, a summer storm is more than weather. It's tied to places we've lived, people we've known, and moments we carry with us long after the clouds have passed.
This episode explores both sides of that story.
A note on the format
This episode was built around sound, pacing, movement, and atmosphere. The transcript contains the words, but not the experience. If you haven't listened yet, start there.
👉 Transcript (audio experience recommended)
Final Note
The next time you smell rain before it arrives, you'll know what's happening. You'll know about plant oils, geosmin, and the microbes living beneath your feet. But perhaps you'll also think about something else. A place. A memory. A storm you've been carrying with you for years. Because sometimes the most remarkable things in science aren't hidden in distant laboratories or remote field sites. Sometimes they're waiting in the air just before a summer rain.
ANNOTATED REFERENCES
Bear IJ, Thomas RG. 1964. Nature of Argillaceous Odour. Nature.
https://www.nature.com/articles/201993a0 (paywalled so PDF provided)
➡ The paper that introduced the term petrichor and helped establish the scientific basis for the distinctive smell associated with rain falling on dry ground. The authors identified plant-derived oils accumulating on rocks and soil during dry periods as an important component of the scent released by rainfall.
Gerber NN, Lechevalier HA. 1965. Geosmin, an Earthy-Smelling Substance Isolated from Actinomycetes. Appl Microbiol
https://doi.org/10.1128/am.13.6.935-938.1965 (paywalled so PDF provided)
➡A foundational study identifying geosmin, the compound responsible for the characteristic earthy smell produced by many soil-dwelling bacteria. This work helped establish the microbial contribution to the scent commonly associated with rain and freshly turned soil.
Joung, Y., Buie, C. 2015. Aerosol generation by raindrop impact on soil. Nat Commun.
➡A landmark study demonstrating how raindrops striking porous surfaces can generate tiny aerosol droplets that carry compounds from soil into the air. Using high-speed imaging, the authors showed a plausible mechanism by which geosmin and other odor-producing compounds become airborne during rainfall, helping explain why we can smell rain so quickly.
Polak EH, Provasi JP. 1992. Odor sensitivity to geosmin enantiomers. Chemical Senses https://scispace.com/papers/odor-sensitivity-to-geosmin-enantiomers-v3k95vbij9 (not paywalled but you have to register, so PDF of entire issue provided)
➡Investigated human sensitivity to geosmin and confirmed that people can detect this compound at extraordinarily low concentrations. The study helps explain why the earthy scent associated with rain is so readily perceived even when only trace amounts are present in the environment.
Herz RS. 2004. A Naturalistic Analysis of Autobiographical Memories Triggered by Olfactory Visual and Auditory Stimuli. Chemical Senses.
paywalled https://academic.oup.com/chemse/article-abstract/29/3/217/321318?redirectedFrom=fulltext&login=false (paywalled so PDF provided)
➡Examined how different sensory cues evoke autobiographical memories and found that odors can trigger particularly vivid and emotionally rich recollections. This work provides scientific context for the strong connection many people experience between certain scents—including the smell of rain—and personal memories.
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