Question: What is a stratospheric balloon?

Catherine Rix answered on 13 Mar 2012:

A stratospheric balloon is a balloon, filled with a has like helium, that can reach the stratosphere. The stratosphere is 25-35 km above the Earth (this is three times higher than a normal aeroplane flies) In the stratosphere it’s very cold, there is no air and you are above the ozone layer so there are high levels of UV radiation. Scientists use these balloons to do experiments to find out about the conditions in the stratosphere.