  Dust barriers effectively capture the photon momentum of a central light
source, but low-density channels, along with re-emission at longer wavelengths,
enhance its escape. We use Monte Carlo simulations to study the effects of
inhomogeneity on radiation forces imparted to a dust envelope around a central
star. We survey the strength and scale of an inhomogeneous perturbation field,
as well as the optical depth of its spherical reference state. We run at
moderate numerical resolution, relying on our previous resolution study for
calibration of the associated error. We find that inhomogeneities matter most
when their scale exceeds the characteristic mean free path. As expected, they
tend to reduce the net radiation force and extend its range; however, there is
significant variance among realizations. Within our models, force integrals
correlate with the emergent spectral energy distribution, given a specified set
of dust properties. A critical issue is the choice of integral measures of the
radiation force: for strong deviations from spherical symmetry the relevant
measures assess radial forces relative to the cloud centre of mass. Of these,
we find the virial term due to radiation to be the least stochastic of several
integral measures in the presence of inhomogeneities.
