An infrared radiative transfer model is developed that can simulate the effects of clouds on satellite upwelling radiances at the top of the atmosphere for a range of satellite scan angles. The model allows the calculations of the upwelling radiance for single layers of middle or high clouds and for multilayered clouds. Sensitivity analyses are carried out for the upwelling radiance in the presence of clouds in the Nimbus 6 high-resolution infrared sounder (HIRS) channels.