Staggered grid used for models with nonisothermal layers. The boundary conditions are applied at the top (stellar irradiation) and bottom (internal heat flux) of the model atmosphere, which are also the nth and 0th interfaces, respectively. The pressure and temperature are located at the center of each layer, while the fluxes traversing a layer are computed at the layer interfaces. We further divide each layer into two sublayers during the iteration for radiative equilibrium (see text for details). In the schematic, we have focused on the kth layer and the various quantities associated with its center and interfaces. Quantities marked with an asterisk are temporarily used in the computation, but not stored as the final output. The layers are evenly spaced in the logarithm of pressure.