  Observations of the solar atmosphere show that internal gravity waves are
generated by overshooting convection, but are suppressed at locations of
magnetic flux, which is thought to be the result of mode conversion into
magneto-acoustic waves. Here, we present a study of the acoustic-gravity wave
spectrum emerging from a realistic, self-consistent simulation of solar
(magneto-)convection. A magnetic field free, hydrodynamic simulation and a
magneto-hydrodynamic (MHD) simulation with an initial, vertical, homogeneous
field of 50 G flux density were carried out and compared with each other to
highlight the effect of magnetic fields on the internal gravity wave
propagation in the Sun's atmosphere. We find that the internal gravity waves
are absent or partially reflected back into the lower layers in the presence of
magnetic fields and argue that the suppression is due to the coupling of
internal gravity waves to slow magneto acoustic waves still within the
high-beta region of the upper photosphere. The conversion to Alfven waves is
highly unlikely in our model because there is no strongly inclined magnetic
field present. We argue that the suppression of internal waves observed within
magnetic flux-concentrations may also be due to non-linear breaking of internal
waves due to vortex flows that are ubiquitously present in the upper
photosphere and the chromosphere.

Solar and Stellar Astrophysics