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Hot Air Balloon


When the balloon is full of hot air, it can rise to the ceiling; when the air cools, it comes down again. Can you find the air temperature at which the balloon only just lifts off?

Up, Up, and Away!

We’ve been flying in hot air balloons since 1783, but how does it work? Well, it’s pretty simple – as air inside the balloon warms up, it expands, making the air inside the balloon less dense than the cooler air around it.

Less dense things float, so the balloon begins to rise. As the air in the balloon cools down, the density of the air inside the balloon begins to match the air outside, and the balloon returns to earth.

With a commercial hot air balloon, it is possible to regulate the temperature of the air balloon, so the pilot can raise and lower the balloon at controlled speeds.

Hot air balloon world record

This video shows some footage of a hot air balloon festival where there were 456 balloons; a world record! You can see how the balloons are filled with air before they leave the ground and some of the fires controlling the height of the balloons.

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Look Closer

Welcome to Look Closer, Techniquest's brand new digital tool. We're trialling Look Closer as a way of offering you a closer look at the science demonstrated by many of our exhibits. You'll find visitor sheets, videos, articles on contemporary science as well as fun trails to navigate your way around the exhibition space.

Speak to our Science Communicators to find out more.