Determination of the Conditions of Inception of an Upward Leader From Grounded Objects in Thunderstorm Conditions

The analytical expressions for potentials and electric field $(EF)$ strength of conductive thin elongated spheroids, to which $U_{\theta}$ voltage is applied or which are located in external $EF$ with $E_{\theta}$ strength are systematized. These expressions have been used for determination of the grounded objects parameters, which enable inception of the upward leaders from them in thunderstorm conditions.