  We apply the picket fence treatment to model the effects brought about by
spectral lines on the thermal structure of irradiated atmospheres. The lines
may be due to purely absorption processes, purely coherent scattering processes
or some combination of absorption and scattering. If the lines arise as a pure
absorption process, the surface layers of the atmosphere are cooler whereas
this surface cooling is completely absent if the lines are due to pure coherent
isotropic scattering. The lines also lead to a warming of the deeper
atmosphere. The warming of the deeper layers is, however, independent of the
nature of line formation. Accounting for coherent isotropic scattering in the
shortwave and longwave continuum results in anti-greenhouse cooling and
greenhouse warming on an atmosphere-wide scale. The effects of coherent
isotropic scattering in the line and continuum operate in tandem to determine
the resulting thermal structure of the irradiated atmosphere.
