What are the gases on a hot air balloon?
Hot air balloons are simply that, hot air. Air inside the balloon or envelope is heated, this becomes less dense than the surrounding air therefore creating buoyancy.
The principle of the Hot Air Balloon is based on the upward movement of hot air. As we know hot air rises up. The burner at the base of the balloon constantly provides hot air inside the balloon. This hot air mass, enclosed in the membrane of the balloon, pushes it up. With the burner constantly providing hot air, the balloon keeps on rising.