The cold air encircles the cartons, maintaining their chill. Meanwhile, warm air drifts up over one's head, to dwell on the supermarket ceiling. Similarly, a balloon infused with heated air, lifts high into the morning sky. Then the pilot fills it with hot air from a propane burner. Once the balloon is erect, the pilot uses the burner and a vent to control the craft.
More hot air inspires the balloon to rise.
To descend, the pilot simply waits for the air to grow cool, or opens up the vent. The air in the top of the balloon can reach 250 degrees. It takes about 20 minutes to inflate a balloon, and 20 minutes also to deflate one. Because propane tanks are bulky, most balloons fly no longer than two or three hours. Generally they travel from 3 to 12 miles.