The over-estimation error of cup anemometers in fluctuating winds

Experiments made in a periodically fluctuating wind current show that Sheppard and Meteorological office pattern cup anemometers over-estimate the mean wind velocity roughly in accordance with Schrenk's analysis except that the overestimation decreases somewhat more rapidly with increase of Schrenk's parameter K (defined in quation 2 below) than is indicated by the analysis. Changing the cup form from the hemispherical to the conical pattern (other characteristics being constant) results in only a slight decrease in the over-estimation error over a limited range of K.