Weak Positive Discharges Leading to Lightning Initiation

Abstract Lightning‐initiating events in the Earth's atmosphere originate within compact regions of space with dimensions on the order of hundreds of meters. In the strongest events the associated current pulses propagate from positive to negative thundercloud charge centers at speeds approaching one tenth of the speed of light, a process referred to as fast positive breakdown. Growing observational evidence indicates that these discharges can also develop with much lower current magnitudes and substantially slower propagation speeds. Here we present a quantitative analysis of weak photoelectric feedback discharges (Pasko et al., 2025, https://doi.org/10.1029/2025JD043897 ) that provides an accurate quantitative interpretation of the available observations in terms of current moments, pulse durations, and positive breakdown velocities. Similarly to volt‐ampere characteristics in conventional discharges the photoelectric feedback discharges exhibit a threshold type quadratic dependence on applied electric field explaining observed broad variability of parameters of these discharges.