Spectrum analysis is applied to satellite observed cloud data over the tropical region of the northern Pacific during the period from October, 1968, through September, 1969. Power spectra of the zonally averaged cloud amount between 160 E and 120 W are first computed along every 2.5 degree latitude band from 30 N to the equator.They reveal three prononuced peaks in the period ranges of 16.7-25.0 days, 7.1-10.0 days, and 3.3-5.0 days. The shorter period fluctuation (3.3-5.0 days), which appears to be a feature of the low latitudes (5-10 N) only, is less significant than the others with longer time periods. The pronounced spectral peaks at 7.1-10.0 day period are encountered in low latitudes near 5 to 10 N. The spectra with a period range of 16.7-25.0 days reveal a significant feature of two maxima in the substropics near 20 N and the tropics near 5-10 N, separated by a minimum near 15 N.Spectra at individual localities are computed at every 2.5 degrees latitude and longitude square mesh. They also exhibit three pronounced peaks at the period ranges of 16.7-25.0 days, 7.1-10.0 days, and 3.3-5.0 days, respectively.From the analysis of the coherence and phase difference with respect to several reference points, one can estimate the wavelength of disturbances associated with major spectral peaks. The wavelength estimated for disturbances with the 16.7-day period is about 7,000 km (10,000 km) at tropical latitudes near 7.5-10 N, and about 15,000 km (13,000 km) at subtropical latitudes near 22.5-25 N during the winter (summer) months. The wavelength for the 10-day period disturbances is measured only at 7.5-10 N, as the fluctuation with this period is not primarily important in more northerly latitudes. It is 7,000 km for the winter months, and 12,000 km for the summer months.As for the 4.5-5.0-day disturbances, the estimated wavelength is about 4,000 km at 7.5-10 N during the winter months, while it is unreliable for the summer months because of somewhat poor coherence.

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Spectrum analysis is applied to satellite observed cloudiness data over the northern and southern Pacific. Power spectra with periods up to 50 days are computed by using continuous data series during the four year period from October, 1965 through September, 1969. They reveal the existence of four pronounced peaks in the period ranges of 33.3-50.0 days, 16.7-25.0 days, 7.1-10.0 days, and 4.0-5.0 days. Spectra in the long period end (33.3-50.0 days) exhibit a significant feature of two maxima (one in the vicinity of 20 N and the other between 5-10 N) over the northern Pacific, while they are not in zonal alignment in the southern Pacific. The shorter period fluctuation (4.0-5.0 days) appears to be significant in low latitudes only. Upon eliminating annual mean variations from the original data series (Jones, 1964, 1971), the daily filtered data are further separated into two groups : four winter half year data and four summer half-year data. An attempt is then made to compute the 4-year mean cloud spectral power with periods up to 25 days in both seasons. This computation proves the existence of three marked peaks with periods 16.7-25.0 days, 7.1-10.0 days and 4.0-5.0 days. The analysis of coherence and phase difference with respect to a reference point (22.5 N, 155 W) reveals the zonal wavelength of cloud disturbances (16.7-25.0 day period) to be about 12,200 km (30,000 km) in the winter (summer) half year. Attempts to obtain wavelength and phase speed for both the 7.1-10.0 day period and the 4.0-5.0 day period were unsuccessful because of a low coherence.