  Internal gravity waves have been observed in the Earth's atmosphere and
oceans, on Mars and Jupiter, and in the Sun's atmosphere. Despite ample
evidence for the existence of propagating gravity waves in the Sun's
atmosphere, we still do not have a full understanding of their characteristics
and overall role for the dynamics and energetics of the solar atmosphere. Here
we present a new approach to study the propagation of gravity waves in the
solar atmosphere. It is based on calculating the three-dimensional
cross-correlation function between the vertical velocities measured at
different heights. We apply this new method to a time series of co-spatial and
co-temporal Doppler images obtained by SOHO/MDI and Hinode/SOT as well as to
simulations of upward propagating gravity wave packets. We show some
preliminary results and outline future developments.
