frostbow

Century Dictionary and Cyclopedia

1. n. A halo of white light attending the sun in cold weather. ; The term is applied popularly and indiscriminately to the white rainbow of 18° to 41° radius, produced by the action of minute globules of water (the colored rainbow due to large drops has a radius of 40° to 42° 30′ )

GNU Webster's 1913

1. n. A white arc or circle in the sky attending frosty weather and formed by reflection of sunlight from ice crystals floating in the air; the parhelic circle whose center is at the zenith.