Units of cross sections about pytmatrix

[jleinonen]

This equation is a consequence of the optical theorem. Note that it's only valid when the scattering geometry is set to forward scattering (as noted in the wiki documentation). You can see this in, for instance, Eqs. 13a and 13b of Chapter 16 of the book Light Scattering by Nonspherical Particles: Theory, Measurements and Applications by Mishchenko et al. Those equations are for attenuation but that's just a multiple of the extinction. The PDF of the book is available here: https://www.giss.nasa.gov/staff/mmishchenko/books.html

Note that the elements of S are in units of length, so multiplying that by the wavelength results in a unit of area.

[ibaris]

Hello jleinonen,

thank you very much for the detailed answer and the reference. I was not aware that S also has a unit of length.

Great work!