Why Does a Helium Balloon Rise?

A balloon floats because it has buoyancy, a lifting power given it by the gas inside it. Some gases are heavier than air and some lighter.

It is only when a balloon is filled with a gas lighter than the air outside it that it will rise. Carbon dioxide, which you blow into a balloon from your mouth is one such gas which is lighter than air. Helium is another.

A balloon filled with helium will stay airborne as long as the gas inside and the equipment attached to it (basket, string, etc.) weigh less than the air in which it is floating.

The balloon will rise until it reaches that height where the weight of the air outside the balloon equals the weight of the air inside it. At that point, it begins to float.

Gradually, though, the air inside does begin to leak out and the balloon starts to fall to earth.

About Karen Hill

Karen Hill is a freelance writer, editor, and columnist. Born in New York, her work has appeared in the Examiner, Yahoo News, Buzzfeed, among others.

2 thoughts on “Why Does a Helium Balloon Rise?”

  1. I am puzzled by this and have looked at a few sites which give the same reason for helium rising.
    So… my question is this – why does a vacuum filled(or more accurately empty) container not rise as the contents, or non contents, are lighter than air and the container displaces a volume of air?

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