What is a sundog and what makes it happen?
(Trsitan, 10 years old, Renton, Washington) A sundog on the right side of a halo around the sun. The globe blocking the sun sits atop a pedestal marking the South Pole. Photo courtesy of U.S. National Science Foundation, 11 Jan. 1999 A: A sundog is a rainbow-like spot in a cirrus cloud. Light shining through ice crystals in the cloud makes a sundog, much like light shining through raindrops makes a rainbow. “They are reddish on the side facing the sun and often have bluish-white tails stretching horizontally away from them,” say David Lynch and William Livingston in Color and Light in Nature. Cirrus clouds–those high fleecy white bands or patches in the sky–are mostly tiny particles of ice. Ice can take on many forms and shapes. The cloud ice, however, is shaped like hex bathroom tiles or stubby pencils each no bigger than the tiniest grains of sand. These ice crystals bend light like a prism, disperse its colors, and cause sundogs. When the crystals line up like tiles on a table, th
