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
Hot air balloon be sealed at the bottom, since the air near the bottom of the envelope is at the same pressure as the surrounding air. In modern sport balloons the envelope is generally made from nylon fabric and the inlet of the balloon (closest to the burner flame) is made from a fire resistant material such as Nomex. Modern balloons have been made in all kinds of shapes, such as rocket ships and the shapes of various commercial products, though the traditional shape is used for most non-commercial, and many commercial, applications. The hot air balloon is the first successful human-carrying flight