  We aim to understand cloud formation in substellar objects. We combined the
non-equilibrium, stationary cloud model of Helling, Woitke & Thi (2008; seed
formation, growth, evaporation, gravitational settling, element conservation)
with the general-purpose model atmosphere code PHOENIX (radiative transfer,
hydrostatic equilibrium, mixing length theory, chemical equilibrium) in order
to consistently calculate cloud formation and radiative transfer with their
feedback on convection and gas phase depletion. We calculate the complete 1D
model atmosphere structure and the chemical details of the cloud layers. The
DRIFT-PHOENIX models enable the first stellar atmosphere simulation that is
based on the actual cloud formation process. The resulting (T,p) profiles
differ considerably from the previous limiting PHOENIX cases DUSTY and COND. A
tentative comparison with observations demonstrates that the determination of
effective temperatures based on simple cloud models has to be applied with
care. Based on our new models, we suggest a mean Teff=1800K for the L-dwarf
twin-binary system DENIS J0205-1159 which is up to 500K hotter than suggested
in the literature. We show transition spectra for gas-giant planets which form
dust clouds in their atmospheres and evaluate photometric fluxes for a WASP-1
type system.
