Rayleigh scattering

Description

../../../_images/rayleigh.jpg

Example of rayleigh volume scattering

Scattering This model reproduces Rayleigh’s scattering. Only the phase function (directional distribution) is computed :

\[p(\theta) = \frac{3}{16 \pi}(1+cos(\theta)^2)\]

The other coefficients, depending on wavelength and composition, are user-definable in the density child spectrum.

For instance, modelling a molecular Rayleigh scattering consists in defining density as follows:

\[\begin{split}density(\lambda) &= N \cdot \sigma \\ &= N \frac{128\pi^5}{3} \frac{\alpha^2}{\lambda^4}\end{split}\]

Where N is the molecule density, σ the molecular cross-section, λ is the wavelength, and α the molecular volume polarizability.

Children Nodes

Spectrum density

The spectral scattering absorption coefficient in m-1

Ocean XML 3.0 example

<scattering type="rayleigh" name="scattering">
     <spectrum type="tabulated" name="density">
             2.6e-07 437.01 2.8e-07 315.926 3e-07 234.546 3.2e-07 178.044 3.4e-07 137.734 3.6e-07 108.306
      3.8e-07 86.392 4e-07 69.788 4.2e-07 57.01 4.4e-07 47.044 4.6e-07 39.174 4.8e-07 32.89 5e-07 27.822
      5.5e-07 18.848 6e-07 13.226 6.5e-07 9.556 7e-07 7.078 7.5e-07 5.356 8e-07 4.126 8.5e-07 3.232
      9e-07 2.566 1e-06 1.68 1.1e-06 1.144 1.2e-06 0.808 1.3e-06 0.586 1.4e-06 0.434 1.5e-06 0.33
     </spectrum>
</scattering>