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Why sky is blue?

  1. Dec 30, 2011 #1
    hi ,
    please tell me why sky is blue?
  2. jcsd
  3. Dec 30, 2011 #2
    Sunlight is scattered by gases and particles in the atmosphere. Blue light is essentially a shorter, smaller wave, and is therefore typically more scattered than the other colors.

    If you look more closely, you'd see its not REALLY "blue". Its bluer straight up, but gets lighter and whiter towards the horizon, etc.

    This is related to why water can look blue too.
  4. Dec 30, 2011 #3

    Vanadium 50

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    If you Google "why sky is blue" you get 786,000,000 hits. The first page is all remarkably good. If there is something you still don't understand after reading that, you might post a specific question here.
  5. Dec 30, 2011 #4
    not quite. Pure water appears blue because it is intrinsically blue.
  6. Dec 31, 2011 #5
    No, not in general but at times , yes... The law is Raleigh's Scattering law.
    Scattering [itex]\propto[/itex]1/λ4

    As wavelength increases scattering decreases.
    Wavelength increases as we go from right to left of the word : VIBGYOR

    We know that the density of atmosphere decreases as we go up higher and higher. By Raleigh's scattering law the diameter of the particle must be greater than the wavelength of a particular colour. So violet is scattered the most in upper region of atmosphere and red the least in lower region. This is why we see somewhat orange colour in atmosphere at times of dusk mainly ( and little at dawn). The blue colour is scattered at upper regions mainly because of shorter wavelength because light is both wave like and particulate. The particulate size of blue is less.
  7. Dec 31, 2011 #6


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    You are saying that distilled water is blue? I don't believe that.
  8. Dec 31, 2011 #7
  9. Dec 31, 2011 #8


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    Last edited by a moderator: May 5, 2017
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