The paper provides a mathematical calculation based on theoretical physics to estimate the current contribution for different types of charge generators existing in the atmospheric electric global circuit. The Earth is represented by a sphere and has a constant potential due to its high conductivity. The generators are composed of one or more point current sources or point charges placed above the sphere. The resulting potential, field, and current flow distributions are obtained by a superposition of the corresponding values of the individual point sources. A new physical model of the global circuits is presented. The calculation of the current budget of the global circuit based on this model shows the generator outputs balanced by an additional current source which provides the Earth with an equally distributed charge density on its surface and gives it a negative potential value. This negative potential enables the Earth to drive, in fair weather areas, a current up to the ionosphere, which then represents the contribution of the generators to the global circuit. ¿ American Geophysical Union 1994