[kirse]

Seriously. I ran a little experiment back one high school summer when I had a helium tank laying around and was bored/curious to know how far your typical lost-to-the-sky "Walmart" helium balloon would travel.

I launched about 50 balloons of varying inflation levels and groups (i.e. 1,2, and 3 balloons) and attached ribbons to them and tied laminated index cards with a numeric-ID and my email address.

I ended up getting a few responses and I believe one of the single balloons traveled over 76 miles before setting down in someone's backyard. The average was something like 50 miles, and that was on a warm night with <5mph wind.

[Gibbon]

I found a similar balloon in a tree once. It had been launched at a birthday party for an 85 year old woman and travelled about 250 kms.

We launched thousands of baloons with index cards, once a year, in primary school but I never received a reply from any of mine.

It's definitely fun though!

[dkokelley]

So then how could a balloon that traveled 100,000ft vertically land within 10km? Maybe the larger mass keeps the wind from pushing it so far.

[ars]

Avoid the jet stream and trade winds. Specifically launch in the "Horse latitudes", and wait for a calm day. The very southern tip of spain is located in the horse latitudes.

[marvin]

The helium balloons probably didn't fall back down to earth as soon as the balloon in the story. But I still think that only 10 km seems pretty remarkable.

[dkokelley]

Good point, the rate of descent might have made a difference. This sounds like a good experiment. Let's release 10 heavy balloons (just like the ones they used) in pairs of 2 at 5 different locations around the world and track where each of them land. I'm not sure what scientific purpose this would serve but it would at least satisfy my curiosity.