On the Determination of the Index of Refraction of the Atmosphere

The index of refraction of radio and optical waves in the lower atmosphere are examined in this note. Relations are derived between neutral density fluctuations and radar and optical reflectivity that results in reasonable values of C sub n squared, the refractivity structure constant. An alternative formulation of C sub n squared is derived using the mean atmospheric density structure and the rate of turbulent dissipation. The resulting values of C sub n squared are very near those calculated from the fluctuation analysis.