Crown flash

Crown flash is a rarely observed meteorological phenomenon in which atmospheric electrical fluctuations realign ice crystals above the crown of a cumulonimbus cloud, producing a brightening followed by aurora-like streamers reaching into the clear sky above the thunderhead. The leading hypothesis holds that sunlight reflects off or refracts through these electrically aligned ice crystals, and that further charging or discharging within the cloud reorients the crystals fast enough to make the light pattern appear to shift and dance; the effect is sometimes called a leaping or jumping sundog, though unlike a sundog it moves and stays localized directly above the cloud rather than off to one side of the sun.