It also produced by refraction of light through ice crystals. When the sun is near the horizon, a sundog would appear as brightly colored spots on either side of the sun. Several phenomena are due to diffraction, or light being bent around objects. A bright ring of light may appear to rest on top of the moon when it is viewed through thin, high clouds. A similar effect is possible with the sun, but because the sun is much brighter, it is more difficult to discern.
Iridescence is another diffraction phenomena.
It occurs when droplets of different size are present within a cloud. When light passes through layers of the atmosphere that have different densities, objects may appear far from its true position. This phenomenon is known as a mirage. A common type of mirage can be seen on hot days when road surfaces absorb a great deal of incoming solar radiation. The air just above the road is relatively cooler and when the light is refracted into our eyes, the pavement appears wet.