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   Frequent Halos  

Halos appear in our skies far more often than do rainbows.  They can be seen on average twice a week in Europe and parts of the United States.  The 22 radius circular halo and sundogs (parhelia) are the most frequent.

In this HaloSim3 simulation the sun is surrounded by a 22 halo and flanked by sundogs. Passing through the sundogs and extending beyond them is the parhelic circle. It sometimes encircles the whole sky at the same altitude as the sun. Upper and lower tangent arcs touch the 22 halo directly above and below the sun. A circumzenithal arc is high above all.   The ice crystals pictured are those forming each particular halo.   Click the simulation text to go to the halo.