Aren't those colorful balloons in the photo a beautiful sight?Every October, several hundred hot-air balloons fly through the air in the Kodak Albuquerque International Balloon Fiesta. More than a million people come to watch the event.
A balloon can fly in the air because hot air rises. To launch a hot-air balloon, the pilot first makes sure the basket is tied securely to the ground, so it doesn't suddenly fly off. Then the fabric of the balloon, or the envelope, is spread on the ground. A fan blows air into the envelope to help open it. As it opens, the pilot uses a propane (a kind of gas) burner to blow hot air into the envelope. The balloon then rises as it is inflated with the hot air until it is upright. When the pilot gives a signal, the basket is untied, and there is lift-off. The pilot uses the propane burner to control how high or low the balloon flies. To go up, he or she turns up the burner to make the air in the envelope hotter. To go down, the pilot just lets the air cool down.
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