Brrr! It’s freezing this morning in Wonderopolis. We woke up to a thick blanket of frost on the grass. Be sure to bundle up as you head to the bus stop. You don’t want to get frostbite!

As you wait for the bus and talk with your friends, you may notice that you can see your breath. If you and your friends all exhale at the same time, you can make a big cloud in the air.

Did you and your friends suddenly turn into cloud-breathing dragons? Or is something else going on here? Why can you see your breath when it’s cold outside but not when it’s hot?

Believe it or not, there’s nothing magical about seeing your breath when it’s cold outside. It’s just science at work.

You may already know that when you breathe in, your body takes in oxygen from the air. When you breathe out, your lungs expel carbon dioxide back into the air. But the breath you breathe out contains more than just carbon dioxide.

When you exhale (breathe out), your breath also contains moisture. Because your mouth and lungs are moist, each breath you exhale contains a little bit of water in the form of water vapor (the gas form of water).

For water to stay a gas in the form of water vapor, it needs enough energy to keep its molecules moving. Inside your lungs where it’s nice and warm, this isn’t a problem.

When you exhale and it’s cold outside, though, the water vapor in your breath loses its energy quickly. Rather than continuing to move freely, the molecules begin to pack themselves closely together. As they do so, they slow down and begin to change into either liquid or solid forms of water.

This scientific process is called condensation. When you exhale when it’s cold outside, the water vapor in your breath condenses into lots of tiny droplets of liquid water and ice (solid water) that you can see in the air as a cloud, similar to fog.

When it’s warm out, though, the invisible water vapor gas stays invisible, because the warm air provides energy that allows the water vapor to remain a gas. As temperatures drop, it’s more likely that you’ll be able to see your breath.

There’s no exact temperature at which condensation will occur. Many environmental factors other than temperature can play a role in condensation, including relative humidity (the amount of moisture in the air). When it falls below 45° F, though, you can usually expect to be able to see your breath.


51 Join the Discussion

1 Star2 Stars3 Stars4 Stars5 Stars  (36 votes, avg. 4.28 out of 5)
  1. The class thought it was very interesting. Also to know around what temperature to start looking for our breath outside. The class thinks it very cool to see your breath when its cold out.Thanks for a great article.

    • We’re so glad you guys thought today’s Wonder was interesting and that you all learned some new things, J. Martin! Thank you for leaving us this great comment to let us know you were here! :-)

    • We think people (like you) who think about stuff are AWESOME, Nick…we call you guys WONDER FRIENDS! Thank you for sharing your comment with us today. We DO have some Wonders about sports! Check out all the sports-related Wonders by clicking on this link that will take you to the SPORTS category here in Wonderopolis: :-)

  2. Why you can see your breath is because when you’re cold, your body functions and then your breath comes out and you can see it. It’s cold outside, that’s why you can see your breath.

    • Hello, Maci! Thanks so much for adding your thoughts about seeing your breath when it’s cold outside! Your comment makes today’s Wonder even more WONDERful! :-)

  3. This article is so cool and that you can see your breath in the cold winter. In the winter, you can get Frost Bite if you don’t put snow gloves on your hand and boots on your feet…I hope you had exellent Christmas. I got a Nitendo 3’Ds. it is so cool to play with, and my dad (who lives in Florida) got it for me and he got my brother Mark an iPod the 4th generation. I have the 1st generation!!!

  4. Hi, I’m Eliz. I just turned 10 and I really liked today’s wonder. I went outside and I could see my breath. P.S. I’m really excited for tomorrows wonder. Love you guys, from Eliz :)

    • Thanks for leaving us such a super nice comment and sharing a little about yourself, Eliz! We think it’s COOL that you went outside to see your breath after you learned why it happens with today’s Wonder…way to go! :-)

  5. You can see your breath because when Hot and Cold air mix together it creates steam.
    Or its just because your breath is really horrid.

    • We don’t know about you, but we don’t think we’d like to see people’s horrid breath very much, Katt and Christin! Thank you both for leaving us a comment to let us know you explored today’s Wonder together! We think that ROCKS! :-)

  6. Today’s Wonder is very cool to breathe and see your breath. I drove through fog on the way to school today, and now I know it’s like seeing your breath.

    • Happy Tuesday, Betzaira! What a great connection you made to this Wonder of the Day®! Thank you for sharing it with everyone in Wonderopolis today! :-)

  7. I loved today’s wonder. I will have to see if I can see my breath when the temperature is 45.
    The thing I like learning about was that our breath has tiny water droplets. I also did not know that when it’s 45 degree outside, you can see your breath I thought that you can only see your breath when it’s really cold outside, like 32 degrees.

    • It sounds like you learned some really neat things about the weather and science by exploring today’s Wonder of the Day®, Megan! We’re sure happy to hear that! :-)

  8. I think you see your breath in the cold because your breath is warm and the air is cold and I think when warm and cold air get mixed up it makes a gas and I think this type of science is called “Thermal Dynamics.”

    • Thanks for leaving us such a GREAT comment and for sharing what you think about seeing your breath when it’s cold outside, Dominque! We think it’s AWESOME that you stopped by this Wonder of the Day® today! :-)

  9. Can I give you a little secret? Mrs. Phillips wanted wonder jars for the class.
    If that’s ok with you? (24 Kids) or 2 jars .
    What was the wistle for ?


    • Hi, Allison! We think it’s great that you are sharing your secret with us! We’re sure Mrs. Phillips appreciates it, too! The whistle is for WONDERing just like the other items inside the Wonder Jar®. Did you know you can make your OWN Wonder Jar®? Just take an empty jar and fill it with all types of things that make you WONDER about the world around you! Then, you can open it, take the items out, and WONDER some more! :-)

    • We think it would be SUPER if you shared what you learned in Wonderopolis today with your friends, Eric! We think it would be even MORE super if you showed them around Wonderopolis so they would get as excited about learning here as you are! :-)

  10. Dear Wonderopolis,
    Thanks for the space links! Today’s wonder was a cool wonder. I think tomorrow’s wonder is why is every snowflake different or penguins.
    Paige 😉

  11. Dear
    Good, I knew that you guys did have a good holiday and if you are wondering what grade I am in? I’m in 5th grade and I’m ten years old. I’ll be 11 in June 2011, but still this article is so cool. It’s the BEST one ever. So how old are you guys??
    THANK YOU for saying LIKE VIEWERS LIKE YOU, but some people call me Barbie. I know it sounds weird, but you can still call me that I don’t really care if you do!!
    Barbie and have a nice day :-)

    • Thanks so much for sharing more about yourself, Barbara (Barbie)! Did you know that every day since Wonderopolis started, there has been a new Wonder of the Day® to explore? Since today’s Wonder about UFOs is Wonder #472, that means we are 472 days old! We’re growing every day, too! We appreciate your comments…keep them coming! :-)

  12. I like it when I see my breath when it is really cold out. I breathe so I can see my breath, then I go through it and it is kind of warm. I think that is really weird but it works. I don’t really like the winter, but I also like it because we can play in the snow and it would be closer to Christmas. Christmas is my fave time of the year with New Years!!

    • We’ll have to try that “walk through your breath” activity the next time it gets cold here in Wonderopolis, Cassidy! Thank you for leaving us this comment and telling us all about it! :-)

  13. I think that when I can see my breath, IT IS TOO COLD!!!!! Bu,t I do like to see my breath sometimes because I like to have snow on the ground and obviously you need to see your breath when there is snow on the ground!! I think seeing your breath is so-so, in my opinion.

    • We appreciate your opinion, Hannah! We think the world wouldn’t be such a WONDERful place to live if everyone felt exactly the same about everything! We like it when it snows, too! :-)

  14. Hey, guys. Have I ever told that my nickname is Kode? Yep, you could call me Kode though. But, anyway, this was a cool article. Thanks for posting.

    • Thank YOU for visiting this Wonder and letting us know you were here by leaving us this super comment, Kode (Austin)! We appreciate your enthusiasm for Wonderopolis! :-)

    • That’s a GREAT Wonder, Regan! It would make a SUPER future Wonder of the Day®! Thanks so much for suggesting it! :-)

    • That’s a great question, Regan! Brains help us think, learn and WONDER! Maybe we will explore brains in a future Wonder of the Day®!

      Which Wonder is YOUR brain’s favorite? Thanks for being a great Wonder Friend! :)

  15. It’s October 12 and at the bus stop my sister always breathes out and says “It’s smoke!!” but she’s only six.
    PS I LOVE LOVE LOVE your wonders! :)

    • Thanks for sharing your comment, Ellie! Isn’t it interesting when we can see our own breath in the air? We understand your little sister was kidding, but we sure are glad that it wasn’t smoke! We learned that smoking is very dangerous and can be harmful to our health. In some areas of the country, October means that Fall is in the air– and the weather begins to get chilly! We hope you and your sister visit us soon for lots of WONDERing! Thanks for sharing your enthusiasm! :)

    • WOHOO, we’re so happy that this Wonder helped you with your homework, MustachePistachio! Keep up the great work– and thanks for commenting today! :)

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>


  • Wonderopolis on Facebook
  • Wonderopolis on Pinterest
  • Print

Have you ever wondered…

  • Why do you see your breath when it’s cold?
  • What is condensation?
  • How cold does it have to be to be able to see your breath?

Wonder Gallery

Try It Out

Ready to see condensation at work right before your eyes? It doesn’t matter whether it’s cold outside right now or not.

If it is cold out, head outside and breathe. Put your hands in front of your mouth. Can you feel how much warmer your breath is than the cold air around you? Does your breath make a cloud?

If it’s not very cold outside right now, try this fun experiment. Find a small mirror and put it in the refrigerator for an hour or so to make sure it’s really cold. When you’re ready, take out the mirror and get ready to breathe on it.

First, take a few deep breaths and notice that you can’t see your breath in the warm air around you. Then, breathe onto the mirror. Do you see how the mirror fogs up when you breathe on it? This occurs because the cold mirror cools the air right around it, which causes your warm breath to condense on the mirror as it hits the cold air. How cool is that?


Still Wondering

Use Illuminations’ Every Breath You Take lesson to focus on problem solving, reasoning and communication skills.


Wonder Categories/Tags

Wonder What’s Next?

Tomorrow’s Wonder of the Day is out of this world! Well, maybe not…

Upload a Photo or Paste the URL of a YouTube or SchoolTube Video.