When a child lets go an average-sized helium balloon, and it flies off, how far will it travel before descending – quora wd gaster battle

Garrick Saito gave an excellent answer. But that was in 2011. Someone asked me to answer in 2016, so I suppose they want to hear my opinion because I have written many answers about balloons. I have been part of several professional balloon launches, but that does not make me an expert on children’s balloons. I’m going to answer, but it’s going to be mostly speculation. I can at least give an educated guess, but it still won’t be much more than a guess.

I expect that the distance traveled by a small balloon could be highly variable depending on the type of balloon, the level of inflation, wind conditions, time of day, type of weather, and probably a bunch of other factors. The distance could be a few feet to several hundred miles. Some might conceivably travel 1000 miles.

The most common types of party balloons are latex balloons and Mylar balloon. Latex balloon (that is, rubber balloons) do not hold helium very well. The helium will diffuse through the skin quite quickly. That’s why such balloons float back down to the floor by morning when left floating up at the ceiling at night. Mylar balloons (usually with a very thin coating of metal for decorative appeal), hold helium MUCH longer. These balloons are much less permeable to helium and can remain taut for days.

If you release a very full latex balloon, it will gain altitude quickly. The helium inside will expand and most likely the balloon will burst soon. It will not go very far at all. A few miles, maybe. Weather balloons are also made of latex and they get up to more than 60,000 feet. But when we launch them, they are far from full. Their volume expands by about a factor of 10 before they burst. If you want a latex balloon to go a long way, you need it already to have lost a lot of its helium so it is barely able to float at all. Then, it will climb very slowly and it may well not burst. It will have room to stretch as it climbs and the helium expands. As it stretches and gets thinner, it will lose helium faster. That’s partly because there is less thickness to diffuse though and partly because there is more surface area to diffuse through. So with luck it will slowly climb to high altitude, but not burst, and gradually lose lift so it will then very slowly lose altitude. This process could take a few hours. If the wind speeds (at altitude) were say, 30 mph, then in 4 hours, it could travel more than 100 miles. But if you get lucky and lose, er launch, your balloon close to sunset, then as it goes up, the balloon skin will get colder than the surrounding air. This will reduce the lift of the helium so it might go up very slowly. Also, the lower temperatures will reduce the speed of diffusion of helium, making it last longer. With luck, it will float all through the night and be almost to the ground at sunrise. Then the sun will warm it, and the helium will get hotter than the surrounding air and send the balloon back up for a few more hours before it finally comes down to ground, perhaps in the afternoon. So you might get almost 24 hours of travel time. At our hypothetical 30 mph wind speed, it could travel over 700 miles. That’s far enough to make it to a neighboring state. Or a few states in the northeast where the states tend to be smaller. It’s very unlikely to make it across any oceans. (This is a US-centric point of view). A balloon could easily cross the English Channel from England and end up somewhere in France.

Now a mylar balloon is a lot different. I should say, please don’t go launching a bunch of mylar balloons. They are coated in metal and they conduct electricity well enough to short out power lines. These balloons do short of power lines once in a while. A mylar balloon holds helium much longer. But if you launch a full mylar balloon, it will climb fast and pop pretty soon. Same as a full latex balloon. So you want the balloon to have lost enough helium so it barely climbs, same as for the latex. But the mylar balloon is a lot stronger than a latex balloon. So it can climb to an altitude at which it becomes taut and then it will not climb much higher. It will be strong enough to withstand further expansion of the helium, and will now float at a constant equilibrium altitude. This is technically referred to as a superpressure balloon. Large superpressure balloons flown by NASA have lasted more than 30 days and circumnavigated the earth (at much higher altitudes where the winds speeds are also much faster). So our small superpressure mylar balloon could conceivably stay afloat for several days. Maybe even a week. Then it could travel a few thousand miles. It becomes possible (although still very unlikely) for it to cross an ocean. Another advantage of a mylar balloon is that it is less likely to burst when hitting a branch of a tree, for example. So it could also blow a long way across the ground after it no longer has enough helium to float properly. Hey, it might cross the Sahara desert and go a few hundred miles more after it can no longer fly.