SIGNIFICANCE OF ANISOTROPY AND THE OUTER SCALE OF TURBULENCE FOR OPTICAL AND RADIO SEEING

The small value found for the outer scale of turbulence (namely, less-than-or-equal-to 5 m) implies a narrow range of validity for application of Kolmogorov's law to calculate the atmospheric limitations to the performance of telescopes and interferometers. Optical and radio seeing measurements are analyzed in support of a proposed turbulence spectrum which exhibits a spectral gap for scales (and hence interferometer baselines) between approximately 10 and 1500 m but which obeys a 5/3 power law between 1500 and 20,000 m. The implications for forecasting the performance of optical and radio telescopes and interferometers are important.