Abstract
Simultaneous measurements of radar reflectivity and radio refractive index at several altitudes in cleat air convection have been made. The experimental data were compared with the theoretical relationship which relates the reflectivity to the refractivity spectrum. The agreement between the measurements and the theory is excellent and shows that the radar return in clear air are the result of, and can be quantitatively described as being from, fine-scale refractivity fluctuations due to turbulent mixing. Further, the data give strong support to the −5/3 spectral decay of the refractivity spectrum in the inertial subrange.