The approach to the investigation of submicron atmospheric aerosol properties, developed over many years and conventionally called ‘the method of active spectral nephelometry’, is described in this paper. This approach is based on the principle of the separate study of the processes of variability of the dry matter of aerosol particles under the effect of external geophysical factors and their condensation activity supplemented by improved investigation of the physicochemical properties of particles by means of artificial influences and the technique for solving the inverse problem. Techniques for measurements and interpretation of data are presented, including solving the inverse problems of light scattering. The efficiency of the method for the study of the parameter of condensation activity and the growth factor of particles is shown based on the data of measurements in the real atmosphere. The results of thermo‐optical investigations of a submicron aerosol are presented. Seasonal and interannual behaviours of the optical parameters measured and microphysical characteristics of aerosol in the near‐ground layer of the atmosphere of west Siberia are analysed using the data from long‐term observations.