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Originally Posted by Dr Nigel
We do see "violet" light, but it activates only our blue-sensitive cones (and not as strongly as does blue light). Sky-blue light also activates our green-sensitive cones very slightly. What we see as sky-blue contains a little bit of green (but only in the way we perceive it).
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Yes, perhaps it's time for a graph of our
responses of our three types of cones. [The blue end coloring looks correctly aligned to wavelength to me, but not the red end.]
[Added: notice how insensitive our cones are to violet.]
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You know how the sky has different shades of blue? Well, a part of that is determined by differences in the spectrum of light that actually enters our eye. Where the sky is an intense, deep blue, that is mostly the shorter-wavelength stuff. Where it looks a bit less intense (and not just the "washing-out" effect caused by looking through more atmosphere, as the sky overhead can appear different shades of blue at different times of day and on different days), there are some slightly longer "blue" wavelengths involved as well.
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I do not quite follow this. Are you saying a little more green exists overhead at certain times of the day to cause blue to lighten, regardless of other effects? That makes some sense near noon time, I suppose.
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Anyway, I thought there were two effects at work - one scattering (absorption / re-emission at different intensities for different wavelengths) and one refractive.
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How do you see refraction contributing?