According to the results of studies on eruptive clouds (EC) at active volcanoes around the world, a negative volumetric electrostatic charge has been found to predominate in EC. As a rule, this charge is located in the middle region of the cloud, with positive charges localized in the upper and lower parts. This model has also been confirmed for the active Ebeko volcano (Is. Paramushir). The article (Akbashev and Makarov in J. Volcanol. Seismolog. 17:134–146, 2023) presents studies based on long-term observations of the atmospheric electric potential gradient (PG) for the period from October 1, 2018 to December 1, 2020. As a result of observations during the specified period, 179 cases of EC propagation were recorded in cloudless or low-cloud conditions, accompanied by changes in PG. The analysis of PG responses and atmospheric wind stratification made it possible to determine the location of bulk electrostatic charges in EC. The predominant charge is negative and is located in the upper part of the cloud. The positive charge is located in its lower region. To explain the nature of the negative volume charge, a physical experiment was conducted. Ash was collected from the Ebeko slope and a stand was prepared for the experiment. An ash cloud was simulated and its direction and velocity were set. PG was recorded during the experiment. The design of the stand allows ash to be charged due to the triboelectric effect.