circumhorizontal arc


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circumhorizontal arc

[¦sər·kəm‚här·ə′zänt·əl ′ärk]
(optics)
A halo phenomenon consisting of a colored arc, red on its upper margin; it extends for about 90° parallel to the horizon and lies about 46° below the sun.
References in periodicals archive ?
An 'upside down rainbow' or circumhorizontal arc, is an optical phenomenon formed by the sun shining on and reflecting off ice crystals in high level cirrus clouds to form a halo.
Scientists say a circumhorizontal arc is an optical phenomenon - an ice-halo formed by plate-shaped ice crystals in high level cirrus clouds.