Diffusion of electromagnetic waves in a random manner by air masses in the upper atmosphere, permitting long-range reception, as in scatter propagation. Also known as radio scattering.

1. The change in direction of a particle or photon because of a collision with another particle or a system.

2. Diffusion of acoustic or electromagnetic waves caused by inhomogeneity or anisotropy of the transmitting medium.

3. In general, causing a collection of entities to assume a less orderly arrangement.