This huge halo stretches wide across the sky. It is rare and even more rarely complete. Its colours spread nearly three times wider than those of the 22 halo and together with its larger radius this makes it at least six times fainter.
Rays pass through a side face and an end face of poorly oriented column crystals to form the bow.
The longer the column crystals, the fainter the halo becomes compared to the 22 halo. A faint 46 halo encircles a bright 22 . Always look twice as far out from the sun for fragments of this rarity. When only fragments are visible it can be difficult to distinguish from the supralateral arc and many sightings of the 46 halo are probably supralateral arcs. To help distinguish between the two, look also for a circumzenithal arc - when the sun is less than 32 high that is.