The diurnal cycle in climatology as revealed in National Centers for Environmental Prediction's Reanalysis 1979--1995 has been studied for global gridded data at 0000, 0600, 1200 and 1800 UT. Climatologies have been prepared for each of the four time levels separately. There are substantial differences in, for instance, the 00002 and 0600 UT climatologies, owing to a diurnal cycle and/or what is referred to commonly as atmospheric tides. The semidiurnal tide is quite strong in the mass fields, but with sampling every 6 hours at the Nyquist frequency, some aspects cannot be studied properly. However, a method of interpolation based on spatial harmonic waves moving at an empirically determined speed can be called upon to make an educated guess about the atmospheric tides at any times in between. This interpolation technique is similar to the one published by Van den Dool and Qin <1996>, but the wave speeds are not like the slow Rossby modes but roughly 15¿ westward per hour. We present the global tides in surface pressure thus obtained for every hour of the day for January.¿ 1997 American Geophysical Union