Push a beach ball under water and it shoves back UP. Water lifts anything lighter than itself. Air does the very same thing — it lifts anything lighter than air.
Two balloons. One is stuffed with plain air, one with light helium. Tap each and see which way the air pushes it.
Air-filled flops down. Helium leaps up — it's far lighter than air.
Air isn't the same all the way up. Gravity piles it thick near the ground and leaves it thin way up high. That thin air is where jets like to fly.
Slide up through the sky. Watch how the air specks thin out the higher you climb.
Now let YOUR balloon go. Watch how high it climbs — and it just keeps going and going.
It rises a couple of metres every second, into thinner and thinner air.
One more thing about that rubber…
The rubber is stretchy. Inside, the helium keeps pushing OUT. Outside, the thinning air pushes back less and less… so up there, what happens to the balloon's SIZE? 🤔
You saw it: the higher it goes, the thinner the air, the less it pushes back.
So how does the balloon's trip finally END?
Drag the balloon up the sky ↑ and watch.
