Аннотация:Red sprites, blue jets, elves, halos, gigantic jets, and bursts of roentgen and gamma-rays associated with lightning discharge have been the subject of a great deal of research during recent years. Runaway relativistic electrons are considered as a possible candidate mechanism for explaining such phenomena. Several mechanisms of initiating runaway relativistic electron avalanche (RREA) runaway exist. Traditional theory of RREA implicates cosmic rays as probable source of seeding relativistic electrons to initiate an avalanche. Another theory implies so called “cold runaway” in very strong electric fields (E > 26 MV/m) to produce these seed electrons. Both of these theories compete with the early studies, which put the main emphasis on positive/negative large-scale streamer similar to point-to-plane corona discharge. Estimates and detailed comparison of these mechanisms have been made in order to find possible measurable indicators which could be used in analysis of low-orbiting satellite observations (e.g., CHIBIS-M) to establish the actual contribution of each mechanism.