1. The ratio of polarized to total radiance in some direction. The degree of polarization ranges from 0 percent for unpolarized radiation, typical of direct solar radiation, diffuse solar radiation within clouds, and all terrestrial infrared radiation, to 100% for completely polarized radiation. The degree of polarization of light from a Rayleigh atmosphere with minimal turbidity is close to 100% at a scattering angle of 90°. 2. See polarization.