Stratospheric condensation nuclei and possible solar influences

Balloon-borne measurements of condensation nuclei and H2SO4 molecules in large negative ion clusters have been made in the stratosphere at around 30 km altitude. The nuclei observed were in the 0.01-0.1 micron diameter range. Consideration was given to sunspot activity as a triggering event for ionization of upper atmospheric H2SO4 species and subsequent formation of the nuclei. A numerical model was defined for a steady state between the H2SO4 association and ion recombination in order to determine a critical nucleation rate. It is concluded that condensation nuclei are produced in ion nucleation in an H2SO4 supersaturated polar cloud chamber, with the process being initiated by solar flare particle ionization.