Atmospheric optics wavelengths. A halo (ἅλως; also known as a nimbus, icebow or gloriole) is an optical phenomenon produced by the interaction of light from the sun or moon with ice crystals in the atmosphere, resulting in colored or white arcs, rings or spots in the sky. Many halos are positioned near the sun or moon, but others are elsewhere and even in the opposite part of the sky. They can also form around artificial lights in very cold weather when ice crystals called diamond dust are floating in the nearby air. There are many types of ice halos. They are produced
Aureole effect plane. Although the focused (light) ray cones are actually more or less parallel to each other, the rays from the aureole effect appear to be radiating from the shadow of the viewer’s head due to perspective effects. The viewer's line of sight is parallel and lies within the cones, so from the viewer's perspective the rays seem to be radiating from the antisolar point, within the viewer's shadow. As in similar antisolar optical effects (such as a glory or Heiligenschein), each observer will see an aureole effect radiating only from their own head’s shadow. Similarly, if a photographer holds their