The lift height of a balloon will depend on its strength, or more precisely, how much it can stretch.

## How high the balloon flies away

As the altitude increases, the air becomes rarefied, i.e. the balloon begins to expand to compensate for the pressure. At an altitude of 10 km, it will need to increase by about 3 times, and higher still (ref.: pynt fest).

An interesting fact is that if we use a sufficiently strong and large balloon, it can well fly to the so-called lower space, it is 35 km. It was first demonstrated by Canadian schoolchildren in 2007. They attached a camera to the balloon and set the bar at 35.8 km. Since then similar experiments have been repeated many times by enthusiasts. The average altitude of such experiments is about 20 km.

## How long will the helium balloon hang on the holiday

Balloons are a constant attribute of festive events, so the question of the "lifetime" of the balloon is very relevant, especially if the registration of the balloons is prepared a few hours before the holiday.

A standard size helium-infused balloon will fly for about 8 to 12 hours, after which the helium will gradually escape through the walls of the balloon as the helium molecules are very small and seep through the micro cracks of latex. Now balloons with helium hang much longer, but how is that possible...

In some cases, 8 to 12 hours is enough, but clearly wanted more. That's exactly what Marjorie Burchette of Kentucky USA thought, she kept a balloon shop. With this question in 1983, she approached her husband, Don, to try to solve the problem. Don was a chemical engineer by profession, and it took him almost a year to create a special substance to which he gave the name Hi-float. Hi-float is a liquid plastic that envelopes the balloon from the inside and prevents helium from escaping. With this treatment Hi-float balloon stays in the air for 4-6 days. Don has since refined the formula in 1992 and in 2002, Ultra Hi-float came out, which further doubled the flight time of the helium balloon.