A long wave infrared radiance model has been defined that permits modeling of the radiance reaching an aerial or satellite sensor. Given the kinetic temperature and emissivity characteristics of the target and background and the prevailing atmospheric data (e.g., radiosonde) atmospheric transmission (the LOWTRAN transmission code is used to compute integrated transmission as a function of altitude), upwelled and downwelled path radiance and radiance and contrast at the sensor can be computed. Both Lambertian and specular reflectors can be modeled. The resultant radiance levels were applied to synthetic scenes comprised of silhouettes of ships viewed at various angles and slant paths. By defining certain sensor response functions, the recorded image at the sensor can be modeled. Results are included for viewing in the 8 to 14-micron region from a fixed altitude above ground level through angles from vertical to near horizontal for a single atmosphere.