Raleigh scattering

[katinahat]

So I've been reading up a bit on Raleigh scattering and I'm a little confused.

What is the primary method of Raleigh scattering? Is it that the EM waves pass through slightly different densities of air molecules, causing the more susceptible frequencies (blue light, in the case of visible light in our atmosphere) to refract and scatter? Or is it that light waves excite the air molecules, causing them to vibrate at a similar frequency to the wave, and give off energy similar to the scattered light? I'm sorry if I'm completely off base here-- I learned a basic overview of light scattering in college, but didn't go into much depth and I'm curious now.

Also, as a side note-- Apparently Mie scattering is not frequency dependent, and it scatters light of all wavelengths. I guess that's why light scattered via that method is primarily "white", yes? Why do larger particles follow Mie scattering while smaller ones follow Raleigh scatter? Is it a firm measurement of what's "small enough" to follow Raleigh scattering, or is it a value that is dependent upon the wavelength of the EM wave?

Thank you so much for your time and effort in responding!

[Griffon]

Raleigh scattering is elastic scattering of light by particles smaller than the wavelength of the incident light. "Elastic" because the scattered light has the same frequency as the incident light. The scattered photons have the same energy as the incident photons in other words.

 

One can think of the incident oscillating EM radiation perturbing the electron distribution within the scattering molecules. The induced oscillation of charge within the molecules radiates light at the incident frequency into all directions not just the forward direction of the incident light.

 

I don't know much about Mie scattering except to say that I think it's a more general formulation of light scattering by particles of all sizes. So it includes Raleigh scattering which as I said concerns scattering by particles smaller than the wavelength of the incident light.