How does a hot air balloon adjust its flying height?

A balloon is a sealed bag filled with air or other gases. Balloons can be used not only as toys, but also as vehicles. If the balloon is large enough and the gas inside is lighter than the air with the same volume, the balloon can rise when the buoyancy generated exceeds the weight of the airbag and attached objects (such as hanging baskets). So it can be used to carry observation instruments and passengers. Unmanned balloons loaded with equipment are often used for scientific research on the atmospheric environment at high altitude and sometimes for measuring cosmic rays. Balloons, as aircraft, can usually be divided into two categories: hot air balloons and inflatable balloons. Both of them fly by using the principle that the density of hot air or special gas is lower than that of normal temperature air to generate buoyancy. Hot air balloon mainly adjusts the temperature of the air in the balloon through its own heater, so as to control the balloon's rise and fall. Inflatable balloon mainly controls the lift of the balloon by adjusting the amount of special gas (usually hydrogen or helium) in the airbag. If necessary, the flight state can be changed by abandoning ballast. Hot air balloons have a long history in China. They are called sky lanterns or Kongming lanterns. Joseph Needham, a famous scholar, also pointed out that Mongols used dragon lanterns to transmit signals in the battle of Liezhnitz in 124 1 year. On 1783, the French montague brothers released the first balloon filled with hot air in Europe. French brother Robert was the first person to fly into the sky in a balloon filled with hydrogen. In many different countries in the world, balloons are also used as decorations to celebrate this big day. When some festivals come, balloons of different colors can be seen on the streets in many places. In some opening ceremonies, people will puncture balloons, which symbolizes the important moment of the opening ceremony and can also condense the atmosphere. View original post >>