HotAirBalloon - GOR-47496-97
Increasing the temperature of the air in the balloon leads to loss of gas and a decrease in density.
Hot air balloons are heated with a propane burner, the gases expand and become less dense on warming and rise.
Red Rock Balloon Rally, hot air balloons being filled and taking off.
The annual Red Rock Balloon Rally at Red Rock State Park in Gallup, New Mexico, In December, the balloon rally is the world's second largest with some 180 balloons flying through cliff-lined canyons during the three-day event.