Hot air balloon sea level, and humidity of the air surrounding. On a warm day, a balloon cannot lift as much as on a cool day, because the temperature required for launch will exceed the maximum sustainable for nylon envelope fabric. Also, in the lower atmosphere, the lift provided by a hot air balloon decreases about 3% for each 1,000 meters (1% per 1,000 ft) of altitude gained. Standard hot air balloons are known as Montgolfier balloons and rely solely on the buoyancy of hot air provided by the burner and contained by the envelope. This style of balloon was developed by the
Ballooning at the 1900 Summer Olympics Hot air balloons for manned flight were invented in 1783, but requiring fuel, they proved less practical than the hydrogen balloons that followed almost immediately. Hot air ballooning soon died out, and gas balloons dominated ballooning for nearly 200 years. Gas balloons used hydrogen or coal gas until switching to helium well into the 20th century. The height or altitude of a gas balloon is controlled with ballast weights that can be dropped if the balloon gets too low. In order to land some lifting gas must be vented through a valve. Gas balloons have greater lift for a given