This is a primary rainbow caused by refraction and reflection, and to a minor extent diffraction, of sunlight or moonlight in very small water droplets. It appears on a “screen” of fog or mist. The fog bow consists of a white band, usually fringed with a faint, thin red band on the outside and a faint, thin blue band on the inside. The fog bow is also sometimes known as a cloudbow, mistbow or white rainbow.