September - rain You are here: Home Photo gallery Atmospheric optics Ice crystal halos Wegener arcs


An extensive set of arcs, touching the 22 deg. upper tangent arc over the sun, curving past the zenith, and crossing eachother and the parhelic circle in the anthelion (the point on the circle opposite the sun). They are a very rare occurence. On the photos below, they can be faintly seen crossing the parhelic circle, and on one photo, one can see the left Wegener arc passing over the parhelic circle and the left 120 deg. parhelion. Note that this part of the Wegener arc even shows some spectral colors. The arcs are due to light being refracted and internally reflected in horizontally oriented, pencil-shaped, hexagonal ice-crystals.

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