Helium and Temperature
Does a helium filled balloon rise faster in hot air or
If the only thing made different is air temperature, then helium will rise
faster in cold air. The decreased temperature makes the air more dense,
heavier. This makes the baloon act a little lighter. It rises faster.
Note that other things, such as air pressure and the helium temperature, can
also affect things.
Cold air. It's denser.
If the balloon were in a controlled room, and the air temperature is 0 for
instance the air would be denser and the balloon would rise faster than in a
room filled with 100 degree air, the change of speed would probably be
unnoticeable by eye though. If however, this were done outside and the warm
air was rising itself the balloon may travel faster due to the rising
I would suggest trying it! Get two helium balloons, as close to the same
size as possible. Time how long it takes for one to rise at room temp.
Time the other one in a bathroom or small room that you can heat up (by
running the shower or using a portable heater). Good Luck.
Helium gas escapes from a rubber balloon because it is able to diffuse
through the rubber. You may have noticed that aluminized mylar party baloons
stay inflated much longer because He doesn't diffuse nearly so rapidly
through the Al film.
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Update: June 2012