Nickname for penguins. alo Class of atmospheric phenomenon similar to a rainbow but caused by the refraction of light by ice crystals. The most common halo, called a parhely, shows as a rainbow circle 22° around the sun, sometimes a secondary circle is visible 46° around the sun and in even better conditions other structures are visible: sundogs and Peary's arcs. Right: A special case of Halo with visible Lowitz arcs.