The work continues the analysis of the results of complex expeditionary measurements in the surface atmosphere, some of which have recently been published. It uses data from expeditions of the Laboratory of Geophysical Research of the Faculty of Physics of the Southern Federal University at research stations of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences: 2017 at the Tsimlyansk Research Station in the steppe zone, 2018 and 2019 at the Kislovodsk alpine station located on the Shadzhatmaz plateau, 2.100 m above sea level. With the help of regression analysis, empirical relationships of the electric potential gradient near the earth’s surface and the concentration of aerosols with a diameter of more than 0.1 μm were obtained for four measurement periods. The investigated dependence has a linear character. Judging by the results obtained, the space charge of aerosols for the arid steppe zone is negative. For the Shadzhatmaz plateau, the results indicate the presence of a positive space charge in the atmosphere under high humidity conditions. The discovered facts are considered as a consequence of the differences in the physicochemical properties of aerosol particles under different conditions. Proceeding from the results of measurements at the alpine station, regression analysis revealed a close relationship between the concentration of aerosols and relative humidity for different size ranges of particles, which is well approximated by an exponential function.