  Cold clouds in hot media are quickly crushed, shredded, and then accelerated
as a result of their interaction with the background gas. The persistence of
cold clouds moving at substantial velocities in harsh environments is a common
yet puzzling feature of many astrophysical systems, from quasar absorption
lines probing galactic halos to clouds of dust passing near Sgr $A^*$. Here we
run a set of idealized numerical experiments, subjecting a line of cold clouds
at a series of mutual separations to a hot background wind. We find that this
stream of clouds is able to shield itself from hydrodynamic destruction by
accelerating the hot background material, creating a protective layer of
co-moving gas. We write down a simple diffusion equation that reproduces the
behavior of the simulations, and we discuss the implications for cosmological
gas accretion and G2.
