  The effect of turbulence on a pair of photons propagating together through
the same medium is analyzed. The behavior is compared to the case where these
photons propagate separately through different turbulent media. The analysis is
done with a multiple phase screen approach, by deriving and solving an
infinitesimal propagation equation. We apply these results to the case where
the initial photons are entangled in their spatial degrees of freedom with the
aid of spontaneous parametric down-conversion. It is found that for this input
state, the decay of entanglement in correlated media under the weak
scintillation approximation is quicker than in uncorrelated media. Beyond the
weak scintillation approximation, the entanglement in correlated media decays
slower when it is close to zero --- approaching zero asymptotically as a
function of scintillation strength. This is contrary to the case in
uncorrelated media where entanglement becomes zero at a finite scintillation
strength.
