  The determination of characteristic amplitudes and anisotropy of hot gas
motions in galaxy clusters from observations of the brightest resonance lines
is discussed. Gas motions affect (i) the spectral line shape through the
Doppler effect and (ii) the radial surface brightness profiles in lines during
resonant scattering. Radiative transfer calculations have been performed by the
Monte Carlo method in the FeXXV resonance line at 6.7 eV for the Perseus
cluster (Abell426). It was shown that (a) radial motions reduce the scattering
efficiency much more dramatically than purely tangential motions; (b)
large-scale gas motions weakly affect the scattering efficiency. The
uncertainty in measuring the characteristics of gas motions using resonant
scattering has been estimated for existing and future observations of clusters.
