When a wave or light ray moves from one medium to another its speed changes. The direction of the ray may also change. This property of waves is called refraction and commonly occurs with light rays.

Traditionally, atmospheric refraction is compensated for by an atmospheric dispersion compensator (ADC ... With our current setup, we were able to reduce the initial residual atmospheric dispersion ...

The change in direction of a beam of light as it travels from one material to another is called refraction. The normal is a construction line drawn at right angles to the surface of the glass block.