The main ionization source of the middle and low Earth atmosphere is related to energetic particles coming from outer space. Usually it is ionization from cosmic rays that is always present in the atmosphere. However, in a case of a very strong solar eruption some solar energetic particles (SEP) can reach middle/low atmosphere increasing the ionization rate up to some orders of magnitude at polar latitudes. By means of case studies of solar protons events with different energies of particles and their in uence on various atmospheric parameters it was possible to evaluate the effect of solar (SEP) and galactic (GCR) particles on polar microphysical processes. The case studies of the extreme SEP events show their possible applications for natural variations of the aerosol content. Nevertheless, the effect of the additional ambient air ionization on the aerosol formation is minor, in comparison with temperature effect, and can take place only in the cold polar atmospheric conditions. Possible accompanied tempera