How big are the weather balloons?
The balloons are very big, but they don’t fill them all the way up. When you take a balloon and take it in an airplane, you would find the balloon would get bigger. The air inside the balloon pushes out against the walls of the balloon, and then air outside the balloon pushes back. When you take a balloon up really high, the amount of air inside the balloon stays the same, but there is less air outside the balloon, so less to push back and the air inside the balloon can push out more. The balloon is filled up part way and sent up, but as they go up they get bigger and bigger until they pop. They reach 300 feet across before they pop.
