On May 27, 1931 Auguste Piccard and Paul Kipfer reached an altitude of 15.8 km (51,775 ft) in a balloon. The air density at that altitude is very low so they needed to travel in a pressured gondola. The air at that altitude is also very cold. How were they able to stay warm?

they had to recoup to the thermal insulation of two things the gondola in the travel and in clothes for extreme cold for them

Explanation:

On this trip the researchers used a hydrogen balloon. In general, the temperature drops by about 2ºC / 300 m, so the temperature at that height is of the order of -50 to -60ºC.

    It is not possible to keep the temperature with flames, since oxygen is very scarce and the fire would not occur, in addition to the danger of fire with hydrogen.

   Due to the lack of oxygen at this altitude, pressurized oxygen tanks must be carried out so that the exit at atmospheric pressure is heated.

  Therefore they had to recoup to the thermal insulation of two things the gondola in the travel and in clothes for extreme cold for them

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