Electrostatic field by thunderclouds: threat at ground level

The physics of charge formation and separation within clouds prior to lightning events is still not fully understood. The common and practical, simplified approach based on three lumped charges may conduct to unrealistic predictions, which do not match measured data. An accurate model considering distributed charges in several layers is more in line with actual measurements of charge distributions conducted all over the world and may be used to predict the stress acting upon electrical structures at ground level. Because of the large dispersion of measured situations as a consequence of the stochastic nature of the involved phenomena, a statistical approach is devised and adopted to numerically evaluate the electric field impinging on and the electric potential stressing insulators of a typical medium voltage overhead line without shield wire, located below a thundercloud.