Gas balloon

A gas balloon is a kind of balloon that uses a gas of low density to fly using buoyancy.  Gas balloons sometimes fly very high, very far, and for a very long time.

A gas balloon is different from a hot air balloon.  A hot air balloon uses a fire to lower
the density of air.  A gas balloon does not use fire.

The most common use for gas balloons are to measure the atmosphere.  These are called weather balloons.

Some gas balloons carry people. 

Category:Aircraft