circumzenithal arc


circumzenithal arc

[¦sər·kəm¦zē·nə·thəl ′ärk] (optics) A brilliant rainbow-colored arc of about a quarter of a circle with its center at the zenith and about 46° above the sun, produced by refraction and dispersion of the sun's light striking the top of prismatic ice crystals in the atmosphere, and usually lasting only a few minutes.