An experimental system for directly recording statistics of the intensity of atmospheric turbulence

It is demonstrated theoretically that the ‘filtering’ effects exerted on a turbulence record by taking averages over an interval s, for a total sampling time t, may be reproduced by simple electrical filters as far as the variance is concerned. The smoothed rectified output of such a filter may be recorded on a slowly moving chart and, with the further assumption of Gaussian distribution in the amplitudes of the fluctuations, may be read directly as a statistical mean of the standard deviation. A description is given of an experimental system, and of direct tests of its performance in recording the standard deviation of wind-direction fluctuations when averaged over 5 sec and sampled over 3 min. Proposed applications are briefly outlined.