  In the last decade, the viscous decretion disk model has emerged as the new
paradigm for Be star disks. In this contribution, we propose a simple
analytical model to estimate the continuum infrared excess arising from these
circumstellar disks, in the light of the currently accepted scenario. We
demonstrate that the disk can be satisfactorily described by a two component
system: an inner optically thick region, which we call the pseudo-photosphere,
and a diffuse outer part. In particular, a direct connexion between the disk
brightness profile and the thermal structure is derived, and then confronted to
realistic numerical simulations. This result quantifies how the
non-isothermality of the disk ultimately affects both infrared measured fluxes
and visibilities.
