This report documents a study of low altitude atmospheric radiation transmission conducted by a student-faculty team at California State University, Northridge, School of Engineering. The report was generated under a contract issued by the Air Force Flight Test Center at Edwards Air Force Base. A simple computer program, LARTAP, has been developed. The simplicity of the program makes it easy to modify to suit users requirements. Should detailed testing be required to improve program accuracy, currently available instrumentation has been evaluated. It has also been suggested that a technique involving direct measurement of radiation transmission and utilization or a numerical filtering technique may provide a more accurate model of atmospheric transmission at a test site. (Author).