When snow gets on the electric rail melts and refreezes, it forms a glaze that the high current electricity vapourises. Amazing sparks and arcing create a mini fireworks display. These are hot sparks though, some are pink-purple tint (12000K). This was taken onboard a recently Hitachi motored Class 465 on the SouthEastern railway. Recorded during the historical London snow falls of early December 2010. Calling at London Bridge and London Canon Street.