Scattering of electromagnetic millimeter waves by snow is represented by Rayleigh-Gans theory applied to a polydispersion of equivalent particles that are circular disks. The circular disks are assumed to be randomly oriented. The material that comprises the equivalent particles consists of a homogeneous mixture of ice and air that produces an effective refractive index that is represented by the Bruggemann mixing rule. The fraction of ice in the equivalent particle varies as the size of the largest dimension; it is .35 for the smaller particles and it diminishes as the largest dimension increases. Extinction coefficients, phase functions, asymmetry factors and backscattering cross sections are presented for frequencies 30 < v < 225 GHz. Comparisons with available measurements are presented.