  The next generation X-ray observatory ASTRO-H will open up a new dimension in
the study of galaxy clusters by achieving for the first time the spectral
resolution required to measure velocities of the intracluster plasma, and
extending at the same time the spectral coverage to energies well beyond 10
keV. This white paper provides an overview of the capabilities of ASTRO-H for
exploring gas motions in galaxy clusters including their cosmological
implications, the physics of AGN feedback, dynamics of cluster mergers as well
as associated high-energy processes, chemical enrichment of the intracluster
medium, and the nature of missing baryons and unidentified dark matter.
