Why Does the Sky Look Blue? Rayleigh Scattering

In summary: The blue light is scattered because it has more momentum. When the blue photon enters the atmosphere, it interacts with a polarizable medium (e.g. nitrogen) which causes the photon to deviate from its path.
  • #1
cragar
2,552
3
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 .
 
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  • #2
cragar said:
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

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.

cragar said:
is this similar to white light entering a prism

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

cragar said:
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 .

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

Claude.
 
  • #3
sweet thanks for the answer .
 
  • #4
No worries!

Claude.
 
  • #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.
 
  • #6
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.
 
  • #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 ?
 

FAQ: Why Does the Sky Look Blue? Rayleigh Scattering

1. Why does the sky look blue?

The sky appears blue because of a phenomenon called Rayleigh scattering. This is when sunlight hits the Earth's atmosphere and is scattered by gas molecules and particles, causing the blue wavelengths of light to scatter more than other colors. As a result, our eyes perceive the sky as blue.

2. What is Rayleigh scattering?

Rayleigh scattering is a process in which light is scattered by particles or molecules in the atmosphere. This phenomenon is responsible for the blue color of the sky during the day and the red and orange hues during sunrise and sunset.

3. How does Rayleigh scattering work?

Rayleigh scattering works by scattering sunlight in all directions as it enters the Earth's atmosphere. The shorter blue wavelengths of light are scattered more than the longer red wavelengths, causing the blue color to dominate in our perception of the sky.

4. Does Rayleigh scattering only happen in the Earth's atmosphere?

No, Rayleigh scattering can occur in any medium that contains particles or molecules that are smaller than the wavelength of the light being scattered. This includes the atmosphere of other planets, as well as other substances such as water and dust.

5. Can Rayleigh scattering be observed in other colors?

Yes, Rayleigh scattering can also occur with other colors of light. For example, during a sunset, the longer red wavelengths of light are scattered more, giving the sky a reddish hue. Other factors, such as the amount of particles in the atmosphere, can also affect the color of the scattered light.

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