Abstract: In the atmosphere with an exponential electric conductivity, with given electric potential values in the ionosphere, considering the electric current source by thunderstorm charging, a steady state conservation equation of electric current is solved analytically, and an analytic expression of electric potential distribution is obtained. The expression shows that the effects of thunderstorm charging and ionospheric potential on the atmospheric potential are mainly exerted vertically. Calculation, based on observed current densities of thunderstorm charging and using the expression obtained in this article, shows that the charging by thunderstorm can enhance the potential at the altitude of electric layer to a value similar to that deduced from observations. Calculations also show that the ionospheric potential can influenee the lower atmospheric electricity in fair weather regions through its obvious effects on the potential of electric layer.