Rayleigh Scattering

Changes in directions of electromagnetic energy by particles whose diameters are 1/16 wavelength or less. This type of scattering is responsible for the sky being blue.

Of an electromagnetic wave propagating in a material medium, scattering caused by refractive-index inhomogeneities that are small compared to the wavelength. Note 1: Rayleigh scattering losses vary as the reciprocal of the fourth power of the wavelength. Note 2: Ionospheric scattering is caused partly by Rayleigh scattering.