  We develope a self-consistent description of the Broad Line Region based on
the concept of the failed wind powered by the radiation pressure acting on
dusty accretion disk atmosphere in Keplerian motion. The material raised high
above the disk is illuminated, dust evaportes, and the matter falls back
towards the disk. This material is the source of emission lines. The model
predicts the inner and outer radius of the region, the cloud dynamics under the
dust radiation pressure and, subsequently, just the gravitational field of the
central black hole, which results in assymetry between the rise and fall.
Knowledge of the dynamics allows to predict the shapes of the emission lines as
functions of the basic parameters of an active nucleus: black hole mass,
accretion rate, black hole spin (or accretion efficiency) and the viewing angle
with respect to the symmetry axis. Here we show preliminary results based on
analytical approximations to the cloud motion.
