What’s a birthday party without balloons? No party! There are balloons in all sorts of colors and shapes, and of course you’ve already noticed that some can fly by themselves. But be careful! If you’re not careful, the string will slip and the balloon will rise and dance high into the sky. You have to tilt your head back correctly so that you can still see it. And then he disappeared. Where? We’ll sort that out right away.
But first let’s take a look at why some balloons actually fly. This is not magic, but is due to a certain gas that was filled into the balloon. The gas is called helium, and it is lighter than the air around us. If you let go of a balloon – or rather it is no longer an air balloon but a helium balloon – it rises upwards. This is called buoyancy force. A bottle cork, for example, also develops buoyancy force in a glass of water where it rises to the surface.
If helium-filled balloons don’t get stuck somewhere along the way, they can rise as high as a passenger plane, i.e. around ten kilometers. That’s a hundred football fields stacked on top of each other on the long side – pretty far away. At this altitude, the air pressure changes, causing the helium in the balloon to expand and take up more space. So the balloon gets bigger and bigger until at some point the rubber can no longer hold up. And then: Bang!
Balloons are dangerous for animals
The broken balloon falls back towards earth. But because of the wind it doesn’t land where you let it go. Between takeoff and landing point can be several hundred kilometerssuch a balloon is often on the move for almost a whole day.
Back on Earth it can become a problem. It’s bad for nature when a broken rubber balloon just lies around and isn’t disposed of properly. Birds and other animals think that this could be food. Or they get tangled in the balloon string. This can be quite dangerous for them or even be fatal.
So balloons don’t actually disappear when we let them go. After their journey through the high skies, they crash and become trash. Even if it looks cool to let a balloon go up, you should do it better hold onto!