Scattering

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Scattering
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Types of Scattering in the Atmosphere

• Rayleigh
• Mie
• Geometric

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Rayleigh Scattering in Visible Spectrum

• Blue sky
• Red Sunset
• Blue water (from underwater)

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Rayleigh Scattering

• Wavelength of light is much larger than
  scattering particles
• Blue light 4000 Angstroms, scattering particles
  1 Angstrom (1A10-10 m)

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Intensity of Rayleigh Scattering
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Angular Intensity Factor

• Where f is the angle between the incident beam
  and the scattered light so for non-polarized light

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Rayleigh Scattering

• Can be explained in terms of oscillations of
  dipole atoms when excited by an EM wave
• Derivation explains polarization as well
• See Petty 341-347

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Mie Scattering

• Explains scattering around larger droplets such
  as Corona around the sun or moon, Glory and
  similar phenomena.

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Mie Scattering

• Begin with Maxwells equations
• Derive a wave equation in spherical polar
  coordinates
• Provide boundary conditions at surface of a
  sphere
• Solve the partial differential wave equation for
  dependence on r, q, f.

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Mie Scattering cont.

• The bracket has the form of a Bessel function of
  the first order and

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Mie Scattering cont.

• Fortunately, there are some people who enjoy
  solving these equations and setting up computer
  programs to calculate the results.

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