I would appreciate assistance with a thought experiment I've been having trouble with. What I asked myself was, If I had two Lasers of equal Intensity/power, say 200 milliwatts, one appearing green and the other red, with wavelenghts of say 555 nanometres and the other 660 nm, which laser beam would retain the greatest amount of power when measured at 1 kilometre? I had originally concluded that the red laser would have retained more of it's power because green light is subject to greater Rayleigh scattering than red light. As is graphed here: http://en.wikipedia.org/wiki/Rayleigh_scattering However Upon seeing a similar diagram to the one on the page below on Atmospheric opacity I have come to doubt what now seems to have been a very rash conclusion. http://en.wikipedia.org/wiki/Optical_window So I tried to determine once and for all which would retain more of it's intensity/power and bumped into the Beer-Lambert Law, which seems to be what I am looking for but I have no idea where to find or even guess what would bereasonable values to plug into the equation entitled the ''Beer–Lambert law in the atmosphere''. http://en.wikipedia.org/wiki/Beer–Lambert_law Any assistance would be greeted.