How far can helium-filled balloons fly? 0 13

Elastic balloons, rising into the air, begin to expand due to the decrease in external pressure at altitude. This causes them to continue ascending until they burst at several kilometers high.

Balloons with inelastic shells rise to a level where the air density becomes comparable to the density of helium inside, and then they move with the wind. However, over time, helium begins to leak out, and the balloon descends. If at altitude the balloon enters a jet stream, it can travel thousands of kilometers to the east.

For example, in 2006, a balloon with a message launched in the UK was found in Iraq almost a month after its launch.