Fast particles as initiators of stepped leaders in CG and IC lightnings

A hypothesis about fast particles as possible predecessors of stepped leader is presented in this article. The idea was developed following research on the geometry of the stepped leader. We suggest that the small random deviates of the leader are a consequence of scattering between electron clouds of the particle and surrounding atoms or molecules, while collisions of the nuclei produce forking of the channel. Assuming the fast particle loses its kinetic energy at constant rate we derive equations for its energy, velocity, and position as functions of time. From observations we are able to quantify the initial velocity and the rest mass of the particle. The size and the type of the particle are determined from the geometry of the stepped leader. Results show that according to the hypothesis oxygen atom, either neutral or an ion, is most likely candidate for initiator of a stepped leader. We speculate on the process that might lead to the creation of fast oxygen atoms emanating from a thunder-cell. As they are shot in random directions, initiation of intra-cloud (IC) and cloud-to-ground (CG) lightnings are here explained by the same mechanism. In a view of the hypothesis we address questions of positive CG lightning, CG/IC ratio latitude dependence, and ground attachments.