What makes a hot air balloon rise?
Hot air balloons are an ingenious application of basic scientific principles. Here we will show exactly how the balloon works, what makes it rise and fall and how a pilot is able to maneuver it when it is in the air. The basis of how the balloon works is that warmer air rises in cooler air. This is because hot air is lighter than cool air as it has less mass per unit of volume. Mass can be defined by the measure of how much matter something contains. The actual balloon (called an envelope) has to be so large as it takes such a large amount of heated air to lift it off the ground. For example, to lift 1000 pounds worth of weight you would need almost 65,000 cubic feet of heated air! To help keep the balloon in the air and rising, hot air needs to be propelled upwards into the envelope using the burner (see separate section on burners for more information.) A hot air balloon is made up of 3 main parts: * The Envelope The actual fabric balloon which holds the air * The Burner The unit whi
Any matter having a lower density will float over another matter having higher density. Eg: Timber (rubberised items, bladder filled with air etc) with a density lower than that of water (density = 1) floats on water though timber is solid. The density of air inside a hot air balloon is lower than the density of air outside it. And lo, the balloon has to go up. But then, as the balloon goes up & up, the density of air outside too starts reducing (atmospheric pressure at higher altitudes is lower) and when the two densities inside & outside the balloon match, the balloon stays afloat. It neither will come down nor will go up. However, this is an ideal situation, since the air density keeps changing constantly due to air currents, the balloon will keep moving all around, but slowly.
