Homework for people in cold climates

I heard the coolest thing today. One of my students, who wintered in North Dakota, reported than at temperatures below zero F, when you blow soap bubbles, they freeze and crumple. If you are some where cold, can you please go out with a little kids thing of soap bubbles and see what happens? The physics is straight forward – the soapy water is so so thin that it freezes almost instantly. At the same time, as the air inside (initially warm from your breath) cools, it shrinks. Since the soap bubble has now frozen, it can’t just shrink, but instead crumples.

I really want to see this, but its just above freezing here 🙁

EDIT: Steve sent me the most amazing photo. It is strangely beautiful. I’ve included it big for you to enjoy!bubbles_9999_6.JPG

10 Comments

  1. Freiddie January 16, 2008 at 11:36 pm #

    Cool! (Pun intended)

  2. Richard B. Drumm January 17, 2008 at 12:11 am #

    This cooling sphere stuff reminds me of what they think happened to Iapetus. It explains how it got the seam around the middle. There are also surface features called lobate scarps on Mercury that may have had the same cooling & shrinking as a cause.

    Way cool! Science in a soap bubble! This would absolutely -ROCK- as an outreach experiment to do with kids… Hmmmm…..

    Could you take pictures when you pull this off? Too warm here in Virginia…
    Rich

  3. Steve H January 17, 2008 at 12:42 am #

    Pam;

    I live in Minnesota and it will get below zero in the next couple of days.

    My wife has soap bubbles to tease the cats, so when it gets below zero this week, I will video how the bubbles behave.

    Give me a couple of days….

  4. Dave January 17, 2008 at 12:51 am #

    See the crumpled bubble here, at about 1:15

    http://youtube.com/watch?v=TimU9mgKU1c

    Pam, AstronomyCast so rocks!!!

  5. Joshua Zucker January 17, 2008 at 2:18 am #

    I don’t know if this works. I live in the SF Bay area, so I don’t see below-zero temperatures ever, but at the Exploratorium they have a bubble wand over a cylinder with dry ice at the bottom.

    The bubbles sink VERY slowly, since of course air floats on CO2. The temperature must get pretty low, and the bubbles do (eventually) freeze down there. When they pop, though, it looks more like the top half popping while the bottom half stays frozen.

    http://www.exploratorium.edu/snacks/bubble_suspension.html

    tells us that the bubbles don’t freeze until they’re in contact with the dry ice, so maybe the warm air outside keeps the top half of the bubble still liquid enough to pop fairly normally, and maybe my observations of this thus have nothing to do with what would happen if it were really cold out.

  6. Steve H January 18, 2008 at 7:14 pm #

    I just tried this experiment and the temp was -2 F. The bubbles started out clear and rapidly turned an opaque white. However, when touched they would pop, so I could not call them frozen. However, it was windy and difficult to keep the bubbles from blowin over the roof of the house. I will try this experiment again in to morning, if the wind is slower.

  7. Steve H January 19, 2008 at 11:34 am #

    Temp at -14 deg F and winds calm:

    First test: Bubbles would turn white after 5 seconds of floating in the air and they soon covered my driveway. Left them for one hour, but they remained gooey because of the glycerin in the bubble mixture.

    Second test: Tried a mixture of dishwashing soap and repeated the experiment. These bubbles would turn white but would burst when they touched anything.

    I took several pictures of my driveway covered with semi-frozen bubbles. Send me an email and I will reply these pictures to you.

    Anyway, my wife and I enjoyed doing this experiment, since we had no idea what to expect.

  8. Steve H January 19, 2008 at 2:27 pm #

    Followup:

    After exposure to sub-zero temperatures for four hours, the majority of the bubbles have popped as the winds returned. However, a few bubbles which are located closest to the garage door and protected from the wind, have remained spherical.

    I must conclude that the difference in pressure between the inside and outside of the bubbles were not the cause of the collapse. External forces, such as the wind, were the primary reason why the majority of the bubbles eventually failed.

    Science is always full of surprizes, and I love to perform simple expriments like this. What you expect, is often not what actually happens.

  9. pamela January 20, 2008 at 12:21 am #

    Hi Steve – I just emailed you 🙂 I’m beginning to wonder just how cold it was when my student played with bubbles. I’ll have to ask on Tuesday. I love the scientific process!

  10. Steve H January 21, 2008 at 7:49 pm #

    Images have been emailed.

    Amazingly, I still had a few spherical bubbles remaining after 27 hours in sub-zero weather.

    I was hoping that they would eventually become solid and could be picked up, but the glycerin in the bubble mixture remained gooey and about the consistancy of toothpaste.

    For this experiment, I tried to get the results which were expected, but nothing worked. The dishwasing soap bubbles froze within five seconds, but behaved the same way. Although they would burst on contact with anything, while floating in the air, they remained spherical.

    I had my video camera all setup for this experiment, but there was nothing rapid happening which could be documented. Still pictures of the semi-frozen bubbles on my driveway was a better representation of the results.

    Anyway, thanks for suggesting a rather fun experiment that my wife and I enjoyed doing for you.

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