We investigate the effect of layer optical depth and solar zenith angle on recently developed discrete ordinates models for the diffuse reflectance and transmittance of an optically stationary atmospheric boundary layer. We start with a mathematical formulation of the atmospheric radiative transfer problems dealt with in this article, and we consider a discrete ordinates version of the governing equations. For the sake of continuity, we give a brief account of our recently developed models, and assuming steadiness with respect to the inherent optical properties, we work on the dependence of our models on two target parameters: the relative optical depth of the boundary layer and solar zenith angle. As a result, we get optimized relations for our models in terms of the target parameters. To illustrate the relevance of such relations, we present results of computer simulations using problem sets basic to solar-atmospheric science applications such as environmental remote sensing, radiation dosimetry, and solar power plants.