  We review here the effects of supernovae (SNe) explosions on the environment
of star-forming galaxies. Randomly distributed, clustered SNe explosions cause
the formation of hot superbubbles that drive either galactic fountains or
supersonic winds out of the galactic disk. In a galactic fountain, the ejected
gas is re-captured by the gravitational potential and falls back onto the disk.
  From 3D non-equilibrium radiative cooling hydrodynamical simulations of these
fountains, we find that they may reach altitudes smaller than 5 kpc in the halo
and hence explain the formation of the so-called intermediate-velocity-clouds
(IVCs). On the other hand, the high-velocity-clouds (HVCs) that are observed at
higher altitudes (of up to 12 kpc) require another mechanism to explain their
production. We argue that they could be formed either by the capture of gas
from the intergalactic medium and/or by the action of magnetic fields that are
carried out to the halo with the gas in the fountains. Due to angular momentum
losses (of 10-15%) to the halo, we find that the fountain material falls back
to smaller radii and is not largely spread over the galactic disk, as
previously expected. This result is consistent with the metal distribution
derived from recent chemical models of the galaxy. We also find that after
about 150 Myr, the gas circulation between the halo and the disk in the
fountains reaches a steady state regime (abridged).
