Hot air balloon?

A hot air balloon consists of a bag called the envelope that is capable of containing hot air. Suspended beneath is the gondola or wicker basket (in certain, long distance or high altitude balloons, a capsule) which carries a source of heat capable of producing a sufficient temperature gradient between the air inside the envelope and the surrounding air mass to give enough lift to keep the balloon and its passengers aloft. Unlike gas balloons, the envelope does not have to be sealed at the bottom since the rising hot air only exerts pressure on the upper hemisphere of the balloon to provide lift. In today's sports balloons the envelope is generally made from nylon fabric and the mouth of the balloon (closest to the burner flame) is made from fire resistant material.