Contemporary weather balloons are usually filled with helium. Helium is lighter than air, and this allows the balloon to rise as this gas is lighter than air.
Hydrogen would also work as it has a low density, like helium. And hydrogen is a bit cheaper than helium because it can be "made" from water. But hydrogen is flammable or even explosive, and it is generally not used for that reason.
The balloon is usually filled with hydrogen due to lower cost, though helium can be used as a substitute
Helium these days, for cost reasons, but hydrogen was primarily used in the past because it's a lighter gas.
For more information, check the related link below.
hydrogen, helium, hot air
Helium
The gas inside of a balloon is less dense than the air outside of it if the balloon floats. If the balloon does not float the density of the gas inside of it is equal to or more dense than that around it.
As you rise in elevation, the pressure around you decreases. This lower pressure would cause the balloon to expand, and burst if it was inflated to much originally. By starting it off only partly filled, it will expand to a normal size and not explode.
If there were nothing inside the balloon - a vacuum - the balloon would quickly collapse due to the pressure of the atmosphere outside it. A firmer structure might resist the air pressure, but not a balloon.
Increasing the temperature or pressure of the gas the volume increase.
No
As height is gained the outside air pressure on the balloon is reduced. This reduction allows the gas inside the balloon to expand.
The gas inside of a balloon is less dense than the air outside of it if the balloon floats. If the balloon does not float the density of the gas inside of it is equal to or more dense than that around it.
Inside a balloon there is gas. This gas is normally helium if you want the balloon to fly high, but hydrogen also works.
With helium filled balloons, they rise upwards as the gas inside is of a lower density than the atmosphere around them. The balloon will continue to rise and the gas inside it will expand as the atmospheric pressure decreases with increasing altitude. Eventually, the gas inside the balloon will expand enough to burst the balloon and the balloon will fall back to the ground. When and where this happens depends on weather conditions, air temperature, the rubber used in the balloon, etc.
more gas particles increases the pressure inside the balloon expanding it, since gas particles hit the inside of the balloon.
No, the inside is a gas (air).
The balloon is filled with a gas.
gas
Hydrogen
Because the gas inside expands with the heat
Calucus
No Gas Just hot air which is why it is called a hot air balloon. If you were wondering hot air is lighter than cold air which makes it rise so when it is trapped inside the balloon the whole thing will rise.