Imaged by Matthew Adams (more images) at Granite Bay, California on May 21 with the early afternoon sun 62° high.. ©Matthew Adams, shown with permission.
This immense and colourful ice halo is to be found at two outstretched hand distances beneath the sun and parallel to the horizon.
Summer is the season to look because the sun must be at least 58° high for it to appear.
Hexagonal plate-shaped ice crystals drifting in high and cold cirrus cloud produce the halo. Air resistance aligns them so that their large hexagonal faces are nearly horizontal.
|The circumhorizon arc is often accompanied by another halo half the distance to the sun - a 22 degree halo or a circumscribed halo.|