Why do weather balloons expand as they rise through the troposphere?

Answer 1

The ballon contains a fixed amount of gas producing internal pressure. At the surface, this pressure equals the surface atmospheric pressure. As the balloon rises, the atmospheric pressure drops, allowing the balloon to expand, keeping the internal pressure and external pressure equal. If the balloon is fully inflated at the surface it will burst at higher altitude.

Answer 2

Ever see those massive gas burners on a hot air balloon? That's how they rise: They heat the air inside the balloon. This makes the air inside the balloon less dense and therefore lighter than the surrounding air. Provided the combined weight of balloon, burner, basket, passengers etc, is not too heavy the balloon will then float, sort of like a cork in water.

It's the reason why smoke from a fire will rise up the chimney. Originally it was thought to be a property of the smoke that made it rise and early hot air balloons burned lots of damp straw to make smoke. Luckily for those people who fly in hot air balloons it was realised that just regular air when heated would do the job!

Answer 3

Typically they are filled with helium that is lighter than air and the balloons float up through the denser atmosphere, pulling their payload of equipment upo into the higher levels of the atmosphere.

Answer 4

Because helium weighs less than air.
Balloons rise because the gas inside them, usually helium, is less dense than air.

Answer 5

Air pressure goes down as you get further from the surface of the Earth. So there is less pressure on the outside of the balloon, so the gases inside expand more, making it larger.

Answer 6

Because of the difference in temperature as the balloon risses.

Answer 7

atmospheric pressure