Adapted from Wikipedia...The circumzenithal arc (CZA), also called Bravais' arc, is an optical phenomenon that appears like an inverted rainbow. It comes from refraction of low angle sunlight through horizontally-oriented ice crystals generally in cirrus clouds. It forms no more than 1/4 of a circle centered on the zenith and on the same side as the sun. Its colors are from blue on the inside to red on the outside of the arc. Its colors are purer than those of the rainbow.
It is not uncommon, however it is rarely noticed as it is far overhead. (Thankfully Norah notices things and calls me out to look at them.) It can only form when the sun is at an altitude lower than 32.2 degrees and at its brightest when the sun is at 22 degrees above the horizon.
"Mom! come quick, it is like a rainbow in the sky"
an inverted rainbow? and inverted sundog?
it warranted some research.
Wow! Been looking in the sky for 30 some years and have never seen this! Thank you for capturing and sharing!
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