Saw this display of Mie scattering at the fringe of clouds today in reality (including the inverse thing away from the cloud with the fringe darkening) and started wondering - why is it not in FG?
Of course, the answer is when we designed clouds, all had to be in the vertex shader because making a non-trivial fragment shader floored framerate - but nowadays GPUs are much faster. So I rigged some code to make the MIe term more differential - and - well, what you see above is in fact FG and not reality.
Now I need to get rid of unwanted scattering though... But it might be worth pursuing further...