MODTRAN is used to compute temperature changes due to greenhouse effect described in the page Computing Delta T.
The greenhouse effect reduces the heat, as infrared light, emitted from earth to outer space. Due to continuous variations of partial pressure of the various gases with altitude and their highly complex absorption spectra, it is necessary to use a computer program to determine how much heat is lost to space. MODTRAN is free software (access at http://forecast.uchicago.edu/modtran.html. The form at bottom has the input to begin a study at present conditions. The “Model Output” box at the bottom contains the objective: “Upward IR Heat Flux” Note that physical parameters are 70 km altitude and “looking down.”
MODTRAN has been used for many years, and has been verified by satellite data. Its main application is to support airborne and spaceborne spectrometry and radiometry.
The graph below demonstrates the accuracy of Modtran. Below that is the Input/output panel of Modtran.