On the ground, the weather balloon starts out around 6 feet wide (a tallish man size). That’s a big balloon! But wait! It gets EVEN BIGGER. By the time it gets all the way up into the sky, the air around it has gotten so thin that the balloon grows – and grows – AND GROWS! It can stretch to be around 25 feet wide (a tallish elephant).
And then it pretty much has gotten too big and pops. And the radiosonde, attached to a small parachute, falls back down to the ground where people like me find it.
And mail it back, to see if it can be reused again.
Given how rusty and generally beat up our radiosonde was, I don’t have high hopes. But imagining it in its glory days, floating high above the planet attached to its 25-foot-wide balloon, makes me happy anyway.