  A model is proposed for determining the distances to falling interstellar
clouds in the galactic halo by measuring the cloud velocity and column density
and assuming a model for the vertical density distribution of the Galactic
interstellar medium. It is shown that falling clouds with $N(H I) < \sim
10^{19} cm^{-2}$ may be decelerated to a terminal velocity which increases with
increasing height above the Galactic plane. This terminal velocity model
correctly predicts the distance to high velocity cloud Complex M and several
other interstellar structures of previously determined distance. It is
demonstrated how interstellar absorption spectra alone may be used to predict
the distances of the clouds producing the absorption. If the distances to the
clouds are already known, we demonstrate how the model may be used to determine
the vertical density structure of the ISM. The derived density distribution is
consistent with the expected density distribution of the warm ionized medium,
characterized by Reynolds. There is also evidence that for $z >\sim 0.4 kpc$
one or more of the following occurs: (1) the neutral fraction of the cloud
decreases to $\sim 31 \pm 14%$, (2) the density drops off faster than
characterized by Reynolds, or (3) there is a systematic decrease in drag
coefficient with increasing z.
