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March 13, 2009 4:51 PM

Black balloons in chilly, sunny weather. Will they pop?

I'm marching a St. Patrick's Day parade tomorrow and we will have many green and many black balloons.

I remembered this afternoon that we had trouble with black balloons in the past in sunny weather; we used them for a "stomp the balloon" game at my son's birthday party and they started spontaneously popping almost immediately.

That was in June, though - it's March now and will be probably 25-30 degrees cooler, though probably the same amount of sun.

Do we need to worry about the black balloons popping in the sunlight, or will the colder temperature keep them okay?

posted by Lucinda to science & nature (7 comments total)

No. Balloons are very flexible.
posted by kdar at 5:32 PM on March 13

You should be just fine. Happened to see some black balloons on the street in NYC today (where it was colder than it had any damn right to be, but very sunny) and they were doing all right except for the fact that a few of them got loose and flew up over Madison Square Park into the blue, blue sky.
posted by ocherdraco at 5:40 PM on March 13

The pressure change due to the change in temperature will be negligible. You'll be fine.
posted by Simon Barclay at 7:45 PM on March 13

Remember your high school physics? PV = nRT, with T measured in Kelvins (centigrade above absolute zero). So let's say the temperature inside the balloon went from an ambient temperature of 50 F (about 300 K) up to 100 F (about 325 K). That's an increase of less than 10%...making your baloon expand less than an additional 10%. That's utterly insigificant compared to how you blew it up 20-30 times (that's 2000% to 3000% for the mathematically challenged) from its uninflated size.

The black balloons you used for "stomp the balloons" before were popping "spontaneously" because of grit and other sharp debris on the ground, not because they were black.
posted by randomstriker at 11:44 PM on March 13

randomstriker, I was thinking along the same lines but I wasn't sure how to take into consideration the fact that -- particularly for a balloon, which is very elastic -- both P and V will change with T.
posted by Simon Barclay at 8:11 AM on March 14

The internal pressure of the balloon does increase slightly. But, precisely because the balloon is so elastic, you may as well approximate the internal pressure as constant and in equilibrium with atmospheric pressure acting upon the balloon. Thus the significant increase is in volume, not in pressure.

This makes sense, since it seems that an average man can exert at most 100 cmH20 (0.01 atm) of expiratory pressure , and the average woman much less. Which would mean that the internal pressure of the balloon could never be more than 1.01 atm. And all you experienced balloon blowers know that it's only hard at first with a fresh, uninflated balloon...once you stretch it out or get a bit of air in it, it doesn't take much effort at all to make it bigger.
posted by randomstriker at 2:04 PM on March 14

Well, the balloons were fine, and a great time was had by all at the parade. :)
posted by Lucinda at 2:20 PM on March 14