Upper Tangent Arc and Sun Pillar Above Orsta, Norway

March 04, 2021


Photographer: Geir T. Birkeland Øye 
Summary Authors: Geir T. Birkeland Øye; Jim Foster

Shown above at top center is a rose-colored, upper tangent arc that was observed over Ørsta, Norway, during the afternoon of January 27, 2021. It appears to be tethered to a faint Sun pillar. Tangent arcs are tangent to the 22-degree halo, which isn't visible in this photo. They form as sunlight enters a side face of a columnar shaped snow crystal (either free-falling in the atmosphere or within a cirrus cloud) and then exits through an alternate side face. In order for this particular arc to take shape, the majority of the crystals need to be similarly oriented  -- their long axes are horizontally aligned as they fall.

Photo Details: Canon 700D camera; Sigma 17-70 mm lens.