A hot-air balloon is a lighter-than-air aircraft consisting of a bag, called an envelope, which contains heated air. ... The heated air inside the envelope makes it buoyant, since it has a lower density than the colder air outside the envelope. As with all aircraft, hot-air balloons cannot fly beyond the atmosphere.

Do hot air balloons really fly?

Hot air balloons work because hot air rises. By heating the air inside the balloon with the burner, it becomes lighter than the cooler air on the outside. This causes the balloon to float upwards, as if it were in water.

Are hot air balloons bad?

In the aviation world, hot air balloons are an incredibly safe form of flight, and they have become increasingly safe over time. Accidents are uncommon, and fatalities are even rarer. Between 2000 and June of 2016, only 21 hot air ballooning fatalities were reported in the United States.