Book excerpt: These data were then folded with the time distributions of the temperature and power emission for a nuclear weapon fireball in air to compute the atmospheric transmission of the thermal radiation emitted by a nuclear weapon fireball. Calculated data are presented that shows the dependence of the atmospheric transmittance of the thermal radiation emitted by a nuclear weapon on burst altitude, horizontal range and ground albedo. Utilization instructions, input data formats, a sample problem and the FORTRAN-IV listing of the RRA-90 procedure are given along with the utilization instructions for LITE-III as an aid to those who wish to utilize the codes.