February - halos You are here: Home Photo gallery Atmospheric optics Ice crystal halos 120o parhelia

The 120o parhelia are caused by refraction and multiple reflections of light in horizontally oriented plate-shaped ice crystals. Unlike the 22o parhelia, the 120o parhelia can be visible with any sun elevation, not just low elevations of 40 deg. or less. The 120o parhelia appear at the same elevation as the sun, 120o in azimuth to the left and to the right of it. They are white, colorless spots of light, and because of that, they will easily remain unnoticed if no other clues are present like a parhelic circle (crossing the parhelia) or very bright 22o parhelia. Like the white parhelic circle, the shade of the parhelia is more silvery white than clouds are, and don't look like objects in the sky - rather like reflections (they are, in fact, reflections of sunlight).

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