  HI observations of high-velocity clouds (HVCs) indicate, that they are
interacting with their ambient medium. Even clouds located in the very outer
  Galactic halo or the intergalactic space seem to interact with their ambient
medium. In this paper, we investigate the dynamical evolution of high velocity
neutral gas clouds moving through a hot magnetized ambient plasma by means of
two-dimensional magnetohydrodynamic plasma-neutral gas simulations.
  This situation is representative for the fast moving dense neutral gas
cloudlets in the Magellanic Stream as well as for high velocity clouds in
general. The question on the dynamical and thermal stabilization of a cold
dense neutral cloud in a hot thin ambient halo plasma is numerically
investigated. The simulations show the formation of a comet-like head-tail
structure combined with a magnetic barrier of increased field strength which
exerts a stabilizing pressure on the cloud and hinders hot plasma from
diffusing into the cloud.
  The simulations can explain both the survival times in the intergalactic
medium and the existence of head-tail high velocity clouds.
