  This paper shows that magnetic reconnection could be an important heating
process in cosmic gases. In any volume where magnetized plasmas collide, the
dissipation of magnetic energy via reconnection seems to be unavoidable. Since
most cosmic plasmas are highly conductive, the magnetic field lines are
transported with the gas and no dissipation occurs for the most part of the
volume. This ideal frozen-in property of the magnetic field is broken in small
volumes if field gradients with different field polarity appear, in which
localized dissipative effects, e.g. anomalous resistivity, become important. On
the base of X-ray measurements exhibiting a clear connection of infalling
high-velocity clouds (HVC) with ROSAT "hotspots" we perform resistive
magnetohydrodynamic simulations to investigate the capabilities of magnetic
dissipation as a major heating process in the interaction zone of the cloud
with the halo. The main result is that in the physical environment of a
galactic halo heating by externally driven magnetic reconnection cannot be
suppressed by thermal conduction and/or radiative cooling. Thus, the gas
reaches the maximum temperature given by the magnetic field pressure in the
interaction zone of the HVC with the galactic halo.
