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Hot Air Balloons by Masha and Patsy

We're fascinated by the grace and speed of colorful, gigantic hot air balloons. To learn more about these massive beauties, we went to the Snowmass Hot Air Balloon Festival in Colorado. We were wondering how something bigger than a house can lift off the ground. Our question: How does hot air lift things?

What did we do?
We got permission to ride along with a balloon pilot so we could study how hot air balloons work. We observed the pilot's instruments, including the temperature gauge, which showed the temperature inside the balloon, and the variometer, which showed how quickly the balloon ascends or descends during flight. Every few minutes, we recorded the temperature and the variometer reading. Masha took readings during the low altitudes, while I took the high altitude readings. At the end of their flight, we made a chart of their findings.

What did we find out?
We were surprised to learn that the air in the balloon had to reach 180 degrees Celsius (about 350 degrees Fahrenheit) just to lift off! We also found that it took even higher temperatures to hover above the ground. Finally, we discovered that temperatures must remain high when flying at higher altitudes to avoid descending too rapidly.

What can you do?
  • Ask an adult to help you build your own hot air balloon out of a dry-cleaning bag. Try tying different amounts of weight to it to see how much it can lift.
  • Some balloons don't need hot air to lift. Get a helium balloon and see how much lifting power it has.
  • Use this hot air balloon investigation as a science fair project idea for your elementary or middle school science fair! Then tell us about it!
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whiz quiz
Which creature can carry up to 850 times its own weight?

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