Up, Up, and Away!
Find out how hot air balloons float.
KEITHSZAFRANSKI/GETTY IMAGES (RED CHECKERED BALLOON); UNIVERSAL IMAGES GROUP VIA GETTY IMAGES (HOT AIR BALLOONS)
JIM MCMAHON
Every fall, the skies above Albuquerque, New Mexico, fill with color. It’s the Albuquerque International Balloon Fiesta, the largest gathering of hot air balloons in the world!
Each year, more than 500 pilots bring colorful balloons in outrageous shapes, from pirate ships to haunted houses. No matter their shape, all hot air balloons work the same way. Here’s how they stay afloat.
Great Heights
Hot air balloons have three main parts (see How a Hot Air Balloon Floats). The pilot and passengers ride in the basket. The colorful balloon that fills with air is called the envelope. Attached to the bottom of the envelope are burners powered by tanks of propane, a type of gas.
To take off, the pilot lights the burners, which produce a 12-foot flame. As the air inside the envelope warms, its molecules move faster and farther apart. Soon, the air becomes less dense than the air outside. The balloon lifts off! The upward force that allows the balloon to float is called buoyancy.
Making the flame larger causes the balloon to rise. It can soar as high as 3,000 feet! To travel back to the ground, the pilot opens a vent. This releases hot air through the balloon’s top.
The Air Up There
In the air, the real challenge begins. “You don’t really steer a balloon,” says Caryn Welz, president of Albuquerque’s hot air ballooning association. “It goes where the wind does.”
In Albuquerque, a regular wind pattern helps pilots control the balloons. Cool air from the Sandia Mountains blows south at a low elevation. Warm air rises and blows north. Pilots fly low to go south, then rise higher to travel north.
For Welz, the best part of ballooning is watching a new passenger take in the 360-degree view. “You don’t get that in a plane!” she says.
