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White clouds and blue DVD?

  1. Apr 12, 2007 #1


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    In the sky the less dense parts of the sky scatter blue light and the denser clouds scatter white light. So why does a CD scatter relativly white light and the denser DVD blue light?
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  3. Apr 12, 2007 #2


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    What do you mean? Why is a blue DVD blue? It can be blue because a blue azo dye is present on the data layer. The data layer can also be metallic which might look as if it is scattering relatively white light.
  4. Apr 12, 2007 #3
    The claud and sky scattering has little to do with density.
  5. Apr 12, 2007 #4


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    Some dvds are "denser" than others? What does that even mean? There are several different processes by which DVDs and cds are made, using different materials that have different colors. "density" has nothing to do with it.

    Clouds are not the same composition as clear-blue sky so it isn't correct just to say that a cloud is "denser". The mechanisms to cause the color have nothing at all to do with others. Atomized liquid water is essentially opaque white.
  6. Apr 12, 2007 #5


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    Thanks for the replys.
    I think I should explain myself better:
    First of all, the reason that clouds are white because it is made out of bigger particles than the particles in the "clear-blue sky" (this is what i meant by denser)

    CDs and DVDs store memory by small indentations on the surface. The ones with more memory (DVD) have more indentations that are closer together and smaller.

    But maybe the key here is the smaller, not the closer together. Just like the smaller particles of the clear-blue sky scatter shorter wavelengths (blue) and the bigger particles of the clouds all the wavelengths (white), the DVD with smaller holes scatters blue light and the bigger CD holes white light? Or is the color difference related only to difference in materials?
    Last edited by a moderator: Apr 22, 2017
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