On the physics of high altitude lightning

Abstract

Past and recent observations indicate the presence of lightning at altitudes in excess of 30 km. The phenomenon is manifested as a high altitude optical flash, correlated with the presence of giant thunderstorms in the atmosphere below. This letter presents the first physical model of the process. The model is based on low frequency RF breakdown of the upper atmosphere, ignited by the upward propagating electromagnetic pulses due to conventional low altitude lightning. Horizontal intercloud lightning strokes form the optimal configuration. Horizontal lightning discharges with cloud‐to‐cloud moment charge ∼ 6,000–8,000 C‐km account for the observed level of optical emissions.

Interrelation between ELF transients and ionospheric disturbances in association with sprites and elves

“…Present theories predict that sprite is produced by a large quasi-electrostatic (QE) field due to the large positive charge lowered to the ground by +CGs [Pasko e! al., 1997] and other mechanisms [Milikh et al, 1995;Cho et al, 1998], while elve is believed to occur as a result of the direct heating of the lower ionosphere by the electromagnetic pulse from the lightning [Fukunishi et al, 1996].…”

Red sprites: Lightning as a fractal antenna

“…However, previous considerations of the lightning induced electric fields were based on horizontal [Milikh et al, 1995] [Uman, 1987]. A fractal structure is shown in Fig 2. The current is assigned at every branching point by satisfying current conservation.…”

Sprites, ELF Transients, and Positive Ground Strokes

“…This behavior , , would be consistent with recent observations that positive return stroke progression does not decelerate with height (42), that the brightest illumination of positive return stroke channels aloft lasts for several milliseconds (43), and that up to 50% of the total field change of positive flashes occurs during the first few milliseconds of the return stroke initiation ( 1 1 , 44). sprites are caused by the radiated electromagnetic fields associated with charge acceleration in intracloud flashes (45) or return strokes. W e believe that t h e coincidence of smites with ELF transients iimplying extraordinarily large charge transfer) favors a n electrostatic over a n electromagnetic triggering mech.anism (46).…”