These optical illusions are created by the refraction of sunlight through ice crystals in the atmosphere. For a sun dog to form, there must be hexagonal ice crystals in the sky that float parallel ...

A ray diagram showing refraction at the boundary between air and glass Refraction can cause optical illusions as the light waves appear to come from a different position to their actual source.

The reflection and refraction of light explains how people see images, colour and even optical illusions. Lenses - Edexcel Lenses are precisely shaped pieces of glass that have been developed and ...