We obtained time series of spectra with high S=N and high resolution in wavelength and time of early-type A and late-type B supergiants (cf. Kaufer et al. 1996a, Paperi, and Kaufer et al. 1996b, Paperii for the analysis of the variability of the stellar envelopes). In this work we inspect the time vari- ations of the numerous photospheric line proles in the optical spectrum. We nd complex cyclical variations of the radial ve- locities with a typical velocity dispersion of 3kms 1 . The corresponding equivalent-width variations are less than 1% of their mean if we assume a common modulation mechanism for both radial velocities and equivalent width. We do not nd any depth dependence of the velocity elds in the metallic lines. For Cyg the Balmer lines show an increase of the radial velocity from H27 to H8 by 3km s 1 , which is identied with the on- set of the radially accelerating velocity eld of the stellar wind. The Cleaned periodograms of the radial-velocity curves show the simultaneous excitation of multiple pulsation modes with periods longer and shorter than the estimated radial fundamen- tal periods of the objects, which might indicate the excitation of non-radialandradialovertones,respectively.Theanalysisofthe line-prole variations (LPV) of the photospheric line spectrum reveals prograde travelling features in the dynamical spectra. The travelling times of these features are in contradiction to the possible rotation periods of these extended, slowly rotat- ing objects. Therefore, we suggest that these features should be identied with non-radial pulsation modes, possibly g-modes, of low order (l = jmj < 5).