We separate the variability in a 13-year time series of daily values of the relative angular momentum of the atmosphere (M) into three frequency bands: intraseasonal, seasonal, and interannual. Two methods are used to achieve this separation, and the amount of variance attributable to intraseasonal fluctuations, in particular, is sensitive to the choice made. Seasonal time scales clearly dominate the global momentum series; included in this frequency band is a notable dip in the series early in almost every calendar year. To localize the sources of the frequency band-dependence fluctuations in M, we decompose the data into series of angular momentum values within each of 46 equal-area zonal belts over the globe and form covariances between these belt series and M. Seasonal variations in M represent the residual of opposing contributions from the subtropical jets of the northern and southern hemispheres. Both intraseasonal and interannual variations in M result mostly from behavior in the tropics. ¿1991 American Geophysical Union