How do hot air balloons work?

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Have you ever learned about how hot air rises above cold air? Even if you don’t know about it, you’ve probably experienced it without knowing! Wind, for example, is the result of air in certain places that is heated to be warmer than the air in other places. Because it’s warmer, it rises up, moves other air out of the way, and creates a breeze or a gust! 
The rising of warm air has other uses besides changes in our weather: It can also be used to put a hot air balloon into motion!      
Just like its name implies, a hot air balloon is a special type of aircraft that runs on hot air! There are three main parts of a hot air balloon: The basket where the pilot and passengers sit (also called the “gondola”), the big balloon-like fabric that fills with air and lifts the basket (also called the “envelope”), and the burner which heats the air in the envelope!   
In order to take flight, a hot air balloon pilot first uses a fan to fill the balloon’s envelope with cold air. Once all of the balloon’s passengers are loaded and the pilot has checked that everything is ready, the balloon is released from the ground and the pilot heats the air in the envelope to warm it up! This makes the air in the envelope hotter than the air all around it, and it pulls the whole balloon and its attached basket up into the sky!
To land, a pilot can either let the air in the envelope cool down or release some of it through a special vent at the envelope’s top. Because hot air balloons work on these basic principles of warm air rising above cool air, there isn’t any exact method for steering them. A hot air balloon pilot has to guide the balloon according to the wind by moving the balloon up and down to catch certain breezes! 
by   (whyzz writer)
  • Further information

    Only certain people can operate a hot air balloon. – Hot air balloon pilots receive special training and licenses. (Have you ever thought about how neat it would be to be licensed to work as a balloonist?!)

  • Exploration

    Full of hot air?
    Here are some neat facts about hot air balloons!
    • A hot air balloon can fly up to 12,500 feet in the air! By comparison, the Empire State Building is 1,454 feet tall. That means a hot air balloon can fly higher up than eight and a half Empire State Buildings stacked on top of each other!
    • Most hot air balloons are between 60 and 80 feet tall. (If you aren’t sure how tall that is, think about the fact that most grown-ups are between 5 and 6 feet tall!)
    • On July 2nd, 2002, the adventurer and aviator Steve Fossett became the first person to complete a round-the-world solo trip in a hot air balloon! 
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