On the basis of our present knowledge of the distribution of natural haze particles in the atmosphere, the relation between backscatter intensity and the visual range, or the extinction coefficient, has been analyzed. It can be shown that the various processes which cause the changes in visibility (increasing particle number, changes in particle size distribution, etc.) result in rather different backscatter conditions. Only by a combination of such processes is it possible to explain a relation between backscatter and extinction coefficient as it can be derived from experimental data. It therefore becomes clear that such a relation cannot be a unique one and that it will change from one situation to another.
Robert W. Fenn, "Correlation Between Atmospheric Backscattering and Meteorological Visual Range," Appl. Opt. 5, 293-295 (1966)