How does a hot air balloon work?
Present-day Hot Air Balloon systems closely resemble the original balloons and work on the simple principle that hot air rises. They consist of an envelope to contain the hot air, a system to produce the hot air and a wicker basket to carry the people. Lift is derived from heating the air inside the envelope and descent by allowing some of the air to escape through a vent or by letting it cool naturally.
The basic principle of ballooning is simple: Warm air rises. If warm air is contained in a lightweight bag it will rise until the temperature of the air inside the bag matches the air outside. As the air cools, the bag starts to descend. These days touring balloons carry propane tanks (burners) in the basket or gondola to control heating the air. They are equipped with an instrument panel with a compass, altimeter, fuel gauge, and more. This makes modern balloon rides safe and comfortable, although the burner does get warm and rather loud at times.
the same reason a sealed bottle would float upwards from the bottom of a swimming pool, the hot air is less dense than the outside air and so the balloon is squeezed upwards by the surrounding air. the air becomes more dense as more heat is applied, particles separate more and more when heat is applied. an example of this is ice compared to water and then water vapour, the more heat is applied the further apart and less dense the particles become.
