The present study of ion mobility distributions is based upon data obtained from 197 measurements at the Marsta Observatory. These measurements of ion mobility spectra have been made with the help of the cylindrical condenser. The ion mobilities have been determined from currentvoltage curves in fair weather. As a rule, the break-points (mobility lines) of the voltage-current characteristics appear quite sharply. Thus, different groups of mobilities are obtained. Relationships, between the observed mobilities have been found.