ABSTRACT
Power-spectrum analysis is a measure of the contribution of oscillations with continuously varying frequencies to the variance of a variable. This chapter discusses a spectrum of horizontal wind speed is desired covering a broad enough frequency range so as to include all important contributions to the total variance. It describes testing of the generality of the major peaks and gaps appearing in the spectrum under differing terrain and synoptic conditions. Since the data used to describe the spectral gap cover such a short length of time, the question arises whether the gap might not be a sampling fluctuation. There appear to be two major eddy-energy contributions to the spectrum of horizontal wind speed; one peak occurs at a period of 4 days, and a second peak occurs at a period of 1 minute. Between the two major eddy-energy peaks is a rather broad spectral gap centred at a frequency ranging from 1 to 10cy/hr.
