Radar backscattering from the turbulent clear atmosphere

Radar backscattering from the turbulent clear atmosphere is caused by irregular small- scale fluctuations in the radio refractive index produced by turbulent mixing. This note considers the theoretical relationships between the refractive-index microstructure and the backscattering at radar wavelengths from meters to centimeters. Spectral relationships are clarified and the basic difference between radar sampling and refractometer sampling of refractivity spectra is explained. Theoretical expressions are given for the relationship between the radar reflectivity and spectral representations of the refractive-index variability for the general case, for the isotropic case, and for the inertial subrange.