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Why is the sky blue

  1. Oct 26, 2008 #1
    So the latest i read was that the sky is blue because that is the color of air, just like water is blue for the same reason. Now this short article i read also claimed that sunsets are red because of some property of light that causes it to show different colors when it transmits light as opposed to reflects light.

    What troubles me in the last part is when you look at what prisms do. They split white light up into a rainbow of colors. And I thought that the atmosphere did likewise; when the sun's light hits the earth's atmosphere at an angle we go from white light to reds, oranges.

    So do they both play a part or does the way prisms work not play a part in why we see different colors at sunset?
  2. jcsd
  3. Oct 26, 2008 #2


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    The sky is blue because blue light is scattered best.
    If you aren't looking directly at the sun then any light you see must have been scattered, since blue is scattered most - you see blue, the red light went straight through the atmosphere and out the other side.
  4. Oct 26, 2008 #3

    Vanadium 50

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    As Tom Weller once said, "Why is the sky blue?" "Because it reflects the sea".

    To add to mgb_phys, the same process explains why sunsets are red. When the sun is low in the sky, light travels through a lot of atmosphere, and much of the bluer light gets scattered away, leaving only the red.
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