Ball lightning - Wikipedia, the free encyclopedia:
"Scientists from the Northwest Normal University in Lanzhou, China, published the results in January 2014 of recordings made in July 2012 of the optical spectra of, what was thought to be, natural ball lightning made during the study of ordinary cloud-ground lightning.. At a distance of 900m, a total of 1.64 seconds of high-speed video of the ball lightning and its spectra was made, from the formation of the ball lightning after the ordinary lightning struck the ground, up to the optical decay of the phenomenon. The emission lines of neutral atomic silicon, calcium, iron, nitrogen and oxygen were detected in contrast with mainly ionized nitrogen emission lines in the spectrum of the parent lightning. Oscillations in the light intensity and in the oxygen and nitrogen emission at a frequency of 100Hz, caused by the electric field of the 50Hz high-voltage power transmission line in vicinity, were observed. From the spectra the temperature of the ball lightning was assessed as being lower that the temperature of the parent lightning (<15000-30000K). The observed data are consistent with vaporization of soil as well as with ball lightning's sensitivity to electric fields."
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