Atmospheric Transmittance/Radiance: Computer Code LOWTRAN 4

This report describes a computer code for predicting atmospheric transmittance and the thermal radiation emitted by the atmosphere and earth in the wavelength range from 0.25 to 28.5 micrometers at a spectral resolution of 20/cm. The program is based on the LOWTRAN 3B (1976) computer code and includes the same data package. The effect of aerosol radiance and nitric acid (HNO3) transmittance and radiance is included. The computer code also contains six standard (geographical and seasonal) atmospheric models and four standard aerosol models with an option to replace either with non-standard or measured values. The program can be run in one of two modes, namely, to compute only atmospheric transmittance (as LOWTRAN 3B) or radiance and atmospheric transmittance for any given path geometry.