  We have carried out 2D hydrodynamical simulations in order to study the
interaction between supernova-powered gas outflows from low-mass galaxies and
the local intergalactic medium (IGM). We are specifically interested in
investigating whether a high pressure IGM, such as that in clusters of
galaxies, can prevent the gas from escaping from the galaxy. The interface
between the outflow and ambient IGM is demarcated by a dense expanding shell
formed by the gas swept-up by the outflow. A sufficiently high IGM pressure can
bring the shell to a halt well before it escapes the galaxy. Galaxies in such
high pressure environments are, however, to be ploughing through the IGM at
relatively high velocities. Hence, they will also be subject to ram pressure,
which acts to strip the gas from the galaxy. We have carried out simulations
that take into account the combined impact of ram pressure and thermal
pressure. We find that ram pressure deforms the shell into a tail-like
structure, fragments it into dense clouds and eventually drags the clouds away
from the galaxy. The clouds are potential sites of star formation and if viewed
during this transient phase, the galaxy will appear to have a low-surface
brightness tail much like the galaxies with diffuse comet-like tail seen in
z=1.15 cluster 3C324. In contrast, the relatively unhindered outflows in low
density, low temperature environments can drive the shells of swept-up gas out
to large distances from the galaxy. Such shells, if they intersect a quasar
line-of-sight, would give rise to Ly $\alpha$ absorption lines of the kind seen
in quasar spectra.
