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Why is the sky blue yet the light that reaches the earth white?

  1. Oct 26, 2004 #1
    I've never been able to get an answer as to why is the sky blue yet the light that reaches the earth white. I've been told that the Nitrogen in the earth's atmosphere refracts the white light coming from the sun in a way that makes blue more visible. That's fine, however, what I can't understand, is if somethign up in the atmosphere is making blue more visible, why the light that reaches the earths surface is white. The best I can do is guess that there's some super-refraction going on up high in the atmosphere and somehow the refracted wavelengths re-combine with the other wavelengths of light on the trip to earths surface, but that's probabally wrong.

    Can anyone try to explain this to me?

    Thanks alot,
  2. jcsd
  3. Oct 26, 2004 #2
  4. Oct 26, 2004 #3
    Alright, so that said why the sky appeared blue, but it would seem from that explanation that the red light from teh sun was shot off in some random direction, yet when you shine sunlight through a prism, you get all the colors...
  5. Oct 26, 2004 #4


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    The web page pretty much explained it. If the atmosphere were thicker, the sun would look red, and in fact at sunset when the light has to travel through a lot of air, the sun does look red.

    The atmosphere is thin enough that normally, though blue light and higher frequencies are scattered "more", there's not enough scattering to significantly change the color.
  6. Oct 26, 2004 #5
    A more formal explanation can be found/derived from here
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