The work is an estimate of the global average based on a single - column, time - average model of the atmosphere and surface (with some approximations — e.g. the surface is not truly a perfect blackbody in the LW (long -
wave) portion of the spectrum (the wavelengths dominated by
terrestrial / atmospheric emission, as opposed to SW
radiation, dominated by solar
radiation), but it can give you a pretty good idea of things (fig 1 shows a spectrum of
radiation to space); there is also some comparison to actual measurements.
3 Greenhouse Effect Key Factors Earth - Sun Temperature Differences Greenhouse Gas Concentrations The atmosphere is transparent to incoming solar
radiation (short
wave, high energy), outgoing
terrestrial radiation (longer
waves, lower energy) is absorbed by GHGs.