This display has some of the rarest of ice halos. Phil Smith saw it on 9th January at Smugglerís Notch Ski Resort in Vermont, USA.?The halo's are named are on the ray tracing simulation below. Click the labels for more information. ?Most notable is the possible Kern arc which is a full circle continuation of the colourful circumzenithal arc at top. To see that one is the very rarest of privileges. A faint Hastings arc, Parry supralateral arcs, Moilanen arc and helic arcs are further rarities. The Parry arc just above the upper tangent arc is almost commonplace in that company.?These rare halos demand ice crystals of near perfect optical perfection. Researchers used to travel to the South Pole and elsewhere in Antarctica to study them. Now they shine lamps at night near ski resorts! Why??Snow blowers. The blowers work by sending out small particles that act as nuclei for the growth of snow crystals.† †But some nuclei do not form snow. Instead they escape and can drift in the air for miles. During their drift, nearly perfect halo forming crystals - simple plates and columnar prisms - grow very slowly on them.† †In a sense, ski slope halos are anthropogenic. Donít let that detract from their beauty. When you see them, be sure to look carefully at the circumzenithal arc to check if it circles the zenith as the famous Kern.??