Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Rayleigh scattering ?

  1. Jun 13, 2010 #1
    is the sky blue because , blue light has more energy so it gets scattered to our eye, and red light has less energy so it gets scattered away from our eye , and when the sun sets the angle the light enters our atmosphere changes , is this similar to white light entering a prism and that might be why sunsets are red . ,
    and when the light goes trough the atmosphere are the photons absorbed by the nitrogen and then re-emitted , if not how do the photons interact with the nitrogen and what causes them to be scattered .
  2. jcsd
  3. Jun 13, 2010 #2

    Claude Bile

    User Avatar
    Science Advisor

    Both red and blue light get scattered in the same directions, it's just that blue light scatters more than red, so we see the sky as being blue. Sunsets look red because the light from the sun has to pass through more atmosphere, and blue light has mostly been filtered out.

    EDIT: I should add that the sky looks blue because of shorter wavelengths being scattered more than longer wavelengths AND the fact that our eyes are much more sensitive to blue than say, violet.

    No, the prism effect is because different wavelengths have different refractive indices, has nothing to do with scattering.

    Scattering is NOT absorption and re-emission. Absorption and re-emission involves transitions between real energy states that possess a characteristic lifetime, wheras scattering is more-or-less instantaneous. Scattering occurs as a natural consequence of EM waves interacting with a polarizable medium.

  4. Jun 13, 2010 #3
    sweet thanks for the answer .
  5. Jun 13, 2010 #4

    Claude Bile

    User Avatar
    Science Advisor

    No worries!

  6. Jun 14, 2010 #5
    Claude , when you say sunsets look red because the blue light has mostly been filtered out ,do you mean by filtered that the blue light was absorbed.
  7. Jun 14, 2010 #6


    User Avatar

    Staff: Mentor

    Not absorbed, but instead, scattered. Some of the blue light that is "missing" from the sunset you are looking at, is seen as part of the blue sky by someone else in another location.
  8. Jun 14, 2010 #7
    is blue light scattered more because it has more momentum , When the blue photon enters the atmosphere , you said it scatters because it is interacting with a polarizable medium , what cause the photon to deviate from its path , are the electrons in the nitrogen affecting the electric and magnetic component of the photon ?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook