ELI5: The Science Behind Petrichor - The Smell of Rain
Content Idea & Brief:
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Content Idea Title: "The Secret Science of Rain Smell: What is Petrichor (ELI5)?"
- Alternative Titles: "Why Does Rain Have a Smell? Unpacking Petrichor," "You Know That 'Earthy' Rain Smell? It Has a Name & Science!"
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Recurring Problem/Question it Addresses: People often wonder about the distinct, sometimes dusty or earthy smell that appears when rain starts to fall, especially after a dry spell. They might ask, "What's that smell when rain starts?" or "ELI5 rain smell." This curiosity shows a widespread, relatable phenomenon that many want to understand better.
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Explanation of the Content: This content will offer a simple, easy-to-understand explanation of "petrichor," the scientific term for the smell of rain. It will break down the main components that create this scent:
- Plant Oils: During dry periods, certain plants release oils that collect on surfaces like rocks and soil.
- Geosmin: Geosmin is a chemical compound produced by specific soil-dwelling bacteria (Actinobacteria). Humans are highly sensitive to this compound, detecting it even in tiny amounts.
- The "Release" Mechanism: When raindrops hit the ground, they act as an aerosol, trapping tiny air bubbles that shoot upwards, carrying these aromatic compounds (plant oils and geosmin) into the air for us to smell.
- Optional addition: Briefly mention ozone, which can contribute to the "clean" smell before a storm, though petrichor is more about the earthy scent as rain hits the ground.
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Why this Content Idea is Likely to be Popular/Viral:
- Universal Experience: Almost everyone has noticed this specific smell, making the topic instantly relatable.
- Curiosity Quencher: It answers a common "I've always wondered that!" type of question.
- "TIL" (Today I Learned) Factor: Introducing the term "petrichor" and its scientific basis provides a satisfying piece of knowledge that people enjoy learning and sharing.
- Sensory & Nostalgic: Smells are strongly linked to memory and emotion; explaining a common, often pleasant, smell can evoke positive engagement.
- Simple Science: The explanation, while scientific, can be broken down into easily digestible concepts (oils, bacteria, raindrops splashing), fitting the ELI5 model well.
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Target Audience:
- General Public: Anyone curious about everyday natural phenomena.
- ELI5 Community Members: Users actively seeking simplified explanations for complex topics.
- Science Enthusiasts (Casual): People who enjoy learning interesting scientific facts without deep technical jargon.
- Social Media Users: The "TIL" aspect makes it highly shareable on platforms like Reddit, Twitter, Facebook, and Instagram (especially with a good visual).
- Nature Lovers: Individuals who appreciate and are curious about the natural world.
Origin Reddit Post
r/explainlikeimfive
ELI5 Whats the smell we feel when the rain starts falling?
Posted by u/AloneKhada•06/03/2025
I mean the dust kind of smell, not just the rain
Top Comments
u/mindyourownbetchness
it's called petrichor and it's mostly smells from soil being carried into the air
u/atlasraven
As the internet continues to erode, more and more of those answers will be gone.
u/Northwindlowlander
It's called petrichor- it has various causes but is mostly a chemical called geosmin, which humans (and some other animals) are incredibly good at smelling even in very low amounts.
u/Abridged-Escherichia
The petrichor smell is from bacteria in the soil that produce a chemical called Geosmin which makes up much of the smell.
There is a theory that the bacteria make the smell to attract insec
u/Abridged-Escherichia
The petrichor smell is from bacteria in the soil that produce a chemical called Geosmin which makes up much of the smell.
There is a theory that the bacteria make the smell to attract insec
u/berael
This sub exists to take complicated concepts and explain them in simplified terms.
It is not "Google It For Me And Read It To Me".
u/I_Sett
It means Rock Blood. And ichor is specifically the blood of the gods in Greek myth. So more like 'Rock (god) Blood'
u/jblank62
So sharks detect blood at how many parts per trillion?
1,000,000?
Does that mean that we(humans) *are* better at detecting geosmin than sharks are at water?
u/THElaytox
Fun fact, geosmin is also what makes beets and catfish taste like dirt. Someone bred a variety of beets that are geosmin free that are commercially available. It's fairly heat labile which is
u/elkunas
There's also this thing called ELI5. That's the whole purpose of the sub. Why are you here when you could go join r/igoogledthis
u/-hot_ham_water-
I agree. I don't understand what they get out of writing that. I hate when other people try make someone feel stupid just for asking an innocent question.
u/this_place_suuucks
>'Rock (god) Blood'
🤘
u/FrankGrimesApartment
Same thing with hose water spraying the yard too im assuming?
u/emmettiow
It's petrichor. Also there is a thing called Google.
u/Anal_Herschiser
"THIS GEOSMIN IS MAKING ME THIRSTY!"
u/TexterMorgan
It’s called [Petrichor](https://www.youtube.com/watch?v=Tm5XyRyi6ns) and while many phans dislike it, I actually think it’s a halfway decent musical composition
u/Old_Fant-9074
humans are ~20 times more sensitive to geosmin than sharks are to blood (based on published estimates of lowest detectable concentrations).
u/ivthreadp110
I don't know why people are hating on you for asking a question just saying Google it.
The reason you ask the question is you wanted other people to answer it. Nothing pisses me off more whe
u/BackgroundSquare6179
I couldnt believe this so I looked it up and... yeah, you're right. The numbers differ slightly depending on the source but most I read said humans can detect it in 5 parts per trillion. That
u/mindyourownbetchness
it's called petrichor and it's mostly smells from soil being carried into the air
u/Tjingus
People have already answered 'petrichor and bacteria'
Just to add, an important trait in animals is the ability to find water for survival. We're very good at it, and can detect moisture ver
u/atlasraven
Simple answers like "How many quarts in a gallon?" are for Google. Complex questions like "What is Love?" are for us humans.
u/Pennywhack
petrichor
This scent is a result of several factors, including a chemical compound called geosmin, ozone, and plant oils. Raindrops can also create aerosols that carry these aromatic element
u/fergehtabodit
So the blood of John Bonham for example
Got it
u/jenglasser
AI is notoriously unreliable. It literal makes shit up about a third of the time.
u/Room1000yrswide
What it actually is, or what it's called? For the latter, I think "petrichor" is the word for what you're talking about.
u/Skydiver860
Yes that would mean that we detect it better than sharks detect blood.
u/Skydiver860
We can detect geosmin at five parts per trillion. Sharks can detect blood at one part per million for reference.
u/jamcdonald120
Its called petrichor.
Plants release a toxin that prevents seeds from sprouting (but doesnt kill them), but this toxin is broken down by water. This way the seeds start sprouting when there
u/SucculentVariations
I love pickled beets and always describe the flavor as purple dirt, but enjoyable.
Funny that's actually the taste. 🤣
u/-hot_ham_water-
I agree. I don't understand what they get out of writing that. I hate when other people try make someone feel stupid just for asking an innocent question.
u/jenglasser
Also... Google doesn't have any god damned answers. It POINTS to pages that do. So, if nobody talks about it on other pages Google has nothing to point to.
u/Key_Law4834
Plant Perfume: The oils that plants release onto the dry ground.
Earthy Dust: A substance made by tiny living things in the soil.
u/ivthreadp110
I don't know why people are hating on you for asking a question just saying Google it.
The reason you ask the question is you wanted other people to answer it. Nothing pisses me off more whe
u/Room1000yrswide
What it actually is, or what it's called? For the latter, I think "petrichor" is the word for what you're talking about.
u/shotsallover
Your nose is older and less sensitive to smells now. And you have an emotional connection to the smell that evokes your childhood.
u/shabi_sensei
Ohhhhh this explains why in China, when I said I didn’t like muddy tasting fish I was offered fried farmed fish and it tasted way less muddy!
u/velicue
Tbh ChatGPT is a much better site to use when you want to get answers for this kind of questions compared to Google.
u/Logical-Reach3704
It also brings the question to the attention of others who may not have thought to ask.
u/leoplorodon
Spores exploding after coming in contact with water, geosmin
u/EasilyRekt
Real question is why tf did it smell so bad when I was a kid, it smells neutral if not pleasant now that I’m post-pubescent, but as a kid it was just incessant.
u/evanka5281
I can’t remember where I read/heard this but I believe humans are more sensitive to that smell than sharks are to blood.
u/Northwindlowlander
It's called petrichor- it has various causes but is mostly a chemical called geosmin, which humans (and some other animals) are incredibly good at smelling even in very low amounts.
u/Stop_looking_at_it
It means rock dust
u/jenglasser
Also... Google doesn't have any god damned answers. It POINTS to pages that do. So, if nobody talks about it on other pages Google has nothing to point to.