Realistic syntheses of atmospheric and interstellar extinction spectra

A review is made of realistic numerical line by line spectral syntheses of atmospheric extinction spectra which have many diagnostic applications of spectroscopy to problems of the real world. A 200,001 point atmospheric transmission spectrum between 600 and 780 nm calculated for applications to remote sensing of ocean fluorescence from space is used to illustrate such work. In contrast, the celebrated low resolution extinction spectrum of the interstellar medium is modelled analytically between the far infrared and 1000 Å by taking quantitatively into account the effects of Mie scattering of the interstellar dust grains, Gaussian absorption at 2175 Å, Rayleigh scattering, and absorption by the H2 Lyman bands.