Helium Balloon Question?

Question

When you let go of a helium balloon it goes upwards.

What happens to it when it goes higher and higher into the clouds and you can't see it anymore? Does it go into space? Does it eventually deflate and fall down?

Answer 1

The balloon will continue to rise until the weight of the surrounding air is equal to the weight of the balloon (helium and the balloon shell).

But air becomes thinner (less dense) the higher you go, and therefore there is a theoretical maximum height that a helium balloon can reach. This occurs at about 20 miles above the Earth (that's just over 110,000 feet up, or three times the altitude at which most planes cruise). Since 'outer space' is judged to be about 600 miles above the Earth, the balloon cannot reach outer space.

Eventually the helium starts escaping from the balloon and the deflated balloon will fall back to the ground.

Answer 2

Helium being lighter than air at sea level will cause the balloon to rise.  As the Balloon goes Higher the density of the air decreases so the balloon will reach a given height depending on how much Helium you put in and stay at that height.  If the Helium causes the Balloon to expand beyond it's limits before it reaches max height then it will break.  Otherwise it will gradually lose Helium and sink back to earth.