Originally Posted by
Flugplatz
As opposed to a 'hot-air' balloon-type I presume he is trying to say? Lifting via the heating effect on atmospheric air, rather than contained helium or hydrogen gas which are intrinsically lighter than air
Both types of balloon float or fly for the same reason.
Helium has a lower density than air so it floats above it, make the Helium balloon big enough and the difference is large enough to carry a payload, instruments or people, or bombs, or missiles or chocolate eggs.
Hot air balloons heat the air trapped inside the envelope which reduces its density to less than the surrounding atmospheric air so it rises up for exactly the same reason as a helium balloon. !!!