What makes the sky blue and red in col our?

Question

What makes the sky blue and red in col our?

Answer 1

Because light from the sun is scattering by atoms and molecules in the atmosphere.

Light scattering by particles depends on the relative "sizes" of the photons and the particles.

In the case of visible light, molecules are much smaller than the wavelength of light, so blue light gets scattered much more than red light.

So as light from the sun enters the atmosphere, more blue photons get reflected (not absorbed) by molecules than red photons - but then the blue photons get reflected again and again until they reach us. So the blue light comes from all over, the red light comes almost straight from the sun.

This is also why the sun looks redder at sunrise and sunset - the light's path through the atmosphere is longer when the sun is on the horizon than when it is high in the sky.

Interaction of light with the atmosphere does all sorts of weird and wonderful things that physics can explain:

http://hyperphysics.phy-astr.gsu.edu/Hba...

Answer 2

Is it blue bcus it reflects of the sea an wat not. an red bcus of the sun an the different ways it may be bhind clouds or setting

Answer 3

On a clear sunny day, the sky above us looks bright blue. In the evening, the sunset puts on a brilliant show of reds, pinks and oranges.

The blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air.

However, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue.

As the sun begins to set, the light must travel farther through the atmosphere before it gets to you. More of the light is reflected and scattered. As less reaches you directly, the sun appears less bright. The color of the sun itself appears to change, first to orange and then to red. This is because even more of the short wavelength blues and greens are now scattered. Only the longer wavelengths are left in the direct beam that reaches your eyes.