A spectacular Sun halo display, with a 22° halo, parhelic circle, sundogs and a tangent arc as well as 44° parhelia (sundogs) and 46° halo, was seen in Vemdalen, Sweden Dec 1 2017.
This fantastic range of halo phenomena was filmed by Ludvig Lundin in the Swedish ski resort of Vemdalen. Such dramatic displays usually occur naturally only in polar regions where the ice crystals of frozen fog, known as ‘diamond dust’, refract and reflect the sunlight like tiny prisms.
Near the Poles the crystals can be optically very pure and can have extremely regular hexagonal shapes. But in a place like Vemdalen, such halo-forming ice crystals will have been man-made.
Overnight, the ski resort’s extensive network of snow machines produces ice crystals that are particularly clear and regular.
As these float in the cold air of the morning, they’re just right for producing beautiful and extensive halo phenomena like these.