Aerostatics

The branch of science that deals with the flight of lighter-than-air vehicles, such as balloons, dirigibles, or blimps. These vehicles are filled with hot air or with a gas lighter than the air surrounding it. This gas enables the balloon to rise in the air by displacing more than its own weight of air. Aerostatic lift, which is produced by displacing a mass of air, is different from aerodynamic lift in that it does not require relative motion between the lifting body and the air.