Calculations of atmospheric radiances are compared with observations made in the 15 pm and 4.3 pm spectral regions by the HIRS/2 on TIROS-N. Differences between calculation and observation lead us to make empirical corrections in calculations of atmospheric transmittances. The largest correction is required in the HIRS/2 interval at 690 cm-1. Corrections arealso required in the intervals centered at 703, 2210, and 2270 cm-1. At NOAA's National Environmental Satellite Service, several studies of laboratory spectra show good agreement between observation and calculation in these spectral regions. However, in the 15 μm CO2 Q-branch, classical theory underestimates the observed temperature dependence of widths of spectral lines.