Hot
air rises . The envelope ( the multicolored
compartment) traps a largebubble
of hot air. If the air in the envelope is allowed to cool or ifthe hot
air is "vented"(allowed to escape ) from the top or side of theenvelope
(allowed to escape ) from the top or side of the envelopethe the balloon
will descend. An altimeter ( to measure altitude), a rateof climb meter
, and an envelope temperature gauge are the only instrumentsused in the
balloon . Amazingly, the pilot can control the altitude ofthe balloon within
a matter of inches. |