Features of the mechanism of ball lightning electromagnetic radiation

There is still no complete understanding of the optical radiation of ball lightning. So far no explanation has been found for the variety of its colors, the reasons for the change of color, the generation of light flashes etc. This may be due to incomplete data on the nature of the time dependence of its intensity of its radiation. The analysis of a video film shot in July 2016 near Blagoveshchensk can be of great help in finding the mechanism of ball lightning. For the first time the photo of ball lightning with a normal exposure was obtained, on which the flickering of its radiation and its structure - the core and the shell - are clearly visible. The brightness of ball lightning fluctuates in a chaotic manner, up to a complete extinction for a split second. It is shown that the core is the light emitter, and the shell, while remaining sufficiently transparent, scatters the core's light. It was found that ball lightning retains its size and shape unchanged when the brightness of the glow changes, during a bright flash, and during the final extinction. According to an eyewitness, ball lightning can stop emitting light for several seconds, and then begin to shine again. This may provide a key to explaining the observations of "black" ball lightnings and the cases of its occurrence "as if from nothing". Various options for explaining the process of light emission by ball lightning are considered: thermal radiation, ion recombination, corona discharge. It is shown that the best mechanism for the glow of ball lightning can be explained if we assume that relativistic electrons are the light emitter.