Trace measurement in the upper troposphere and lower stratosphere

As a result of the nuclear weapons tests after the Second World War, various countries began to carry out measurement flights in the upper troposphere and lower stratosphere in order to measure aerosol-bound fission fragments and characterise the fallout. Since the ban on nuclear weapons testing, activity concentrations have generally declined, so that today, only highly sensitive measurement techniques can detect traces of artificial radionuclides. Thanks to technical progress, such measurement flights for trace measurement could also be carried out with drones nowadays, but the high costs for flight authorisation make the future of this means of measurement very uncertain.