The Kern arc is an extremely rare atmospheric optical phenomenon belonging to the family of ice crystal halos.
Near triangular hexagonal crystals with three alternate side faces much shorter than the others allow the Kern arc to occur.
The first photographs of the Kern arc were taken by Marko Mikkilä close to Vuokatti Ski Resort, Sotkamo, Finland on 17 November 2007.
[3] The photographs were in natural sunlight taken from an artificial cloud of ice crystals created by snowguns.
Some samples of ice crystals were also collected, confirming their nearly triangular base.