The high altitude aircraft sampling of aerosols have been carried out at four to seven levels up to 15 km over Poland from 1973 to 1998, and 117 vertical concentration profiles of natural radionuclides and fission products were determined. It was found that the atmospheric concentrations of ²²⁶Ra increased after large volcanic eruptions. The vertical concentrations profile of ²²⁶Ra had a characteristic quasi-parabolic distribution, with the highest concentrations near the ground level and in the stratosphere. Concentrations of ²¹⁰Pb had a more homogeneous vertical distribution, due to the quiescent ascent of its gaseous ²²²Rn precursor from the ground. Vertical concentrations of fission products revealed different types of profiles. After nuclear explosions, the highest concentrations were observed in the stratosphere. The Chernobyl accident reversed the aerial vertical profiles; the main source was near the ground level, but part of the radioactive debris entered also the lower stratosphere. Because of resuspension, the stratospheric residence time of radiocesium from the Chernobyl accident was about three times longer than that of the fallout from nuclear explosions. The resuspension effects and the atmospheric mass transport in the boundary layers are also responsible for the increased concentrations of radiocesium at 1 km altitude observed since 1987 in the situations of atmospheric mass advection from the highly contaminated Chernobyl region.