Sorry, no definitions found.
“For light to enter the cirrus cloud crystals at just the right angle to make a circumhorizon arc, the sun must be at an angle of at least 58 degrees above the horizon.”
“A circumhorizon arc only forms when the clouds contain a specific, hexagonally shaped ice crystal.”
“Several very specific conditions must exist in tandem for a circumhorizon arc to occur.”
Looking for tweets for circumhorizon.