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Polarization of Skylight

  1. Jun 4, 2007 #1
    Hi all, can anyone help me understand in which direction skylight would be polarized at sunset, if the sunset was the in the West? I understand Rayleigh scattering, I'm just not sure about this concept.
  2. jcsd
  3. Jun 4, 2007 #2


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    Are you suggesting that this "skylight" (as opposed to direct sunlight) that is subject to Rayleigh scattering has some sort of polarization introduced to it as a result? I don't know enough about the phenomenon to confirm or deny that.
  4. Jun 4, 2007 #3

    Yes, this is what I am getting at. I was wondering if anyone could explain this to me.
  5. Jun 4, 2007 #4
    I'm not sure of the mechanism, but if your sunglasses are polarised, you need only tilt your head to observe that the light from the sky is also largely polarised.
  6. Jun 4, 2007 #5
  7. Jun 4, 2007 #6

    Chris Hillman

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    With training, humans may be able to detect the polarization of skylight with the unaided eye under some conditions (this is a named effect, but unfortunately I can't recall the name). In general engineering terms, however, the human eye is not well designed, so there is considerable interest in producing robotic vision system which can detect and process polarization in addition to sensory modalities such as saturation and hue. The hope is that this will help autonomous "robowarriors" to distinguish between things they should should at and things they should not.
  8. Jun 4, 2007 #7

    Meir Achuz

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    If you look up at sunset, the light will be horizontally polarilzed, because it becomes polarized perpendicular to the plane of the scattering.
    If you look toward the sun, you will blind yourself.
    But, if you measure the polarization from the direction of the sun,
    it will be polarilzed vertically, because the horizontal polarization scatters away.
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