Astrophysics (index)

Rosseland Mean Opacity

(Rosseland Mean)
(a useful weighted average of opacities at all the wavelengths)

The Rosseland Mean Opacity (or simply Rosseland Mean) is a weighted average of the Opacity of a material, e.g., gas or Plasma through which Electromagnetic Radiation is passing. It is designed to be useful for models that try to do a single calculation covering all Wavelengths rather than treating each wavelength individually, and given the complexity of the effect of a gas on a spectrum, to make such models tractable. It is:

 1    1  ∞ Iν
——— = — ∫   —— dν
<κ>   I 0   κν


  • <κ> - Rosseland Mean Opacity
  • ν - wavelength
  • Iν - Intensity at wavelength ν
  • I - total Intensity
  • κν - opacity at wavelength ν


Referenced by: