why the sky is blue?

Answer 1

OK, here's my standardan attempt at an answer without physics:

I think most people know that sunlight is made up of light of several different wavelengths, and can be split up into the colours of the rainbow. Blue light has the shorter wavelength, and red the longest wavelength.

When sunlight hits the molecules in the atmosphere, the light gets bounced around by the molecules (what actually happens is that the light strikes the molecules and is absorbed, causing the molecules to vibrate and give off, or 're--emit' the lightt; but 'bounce around' is close enough).

Because the blue wavelength is shorter and more energetic, it reacts much more with the air molecules than the red and yellow wavelengths; which tend to pass straight through. Because the blue radiation is re-emitted from the air molecules in all directions ('scattered'), it seems to us looking from the ground that the blue light is coming from everywhere; hence the sky seems blue.

Near sunset, because of the low angle of the sunlight, we see more of the red and yellow wavelendth passing straight through, hence the colours of the setting sun.

BTW: The sky isn't blue because of a reflection of the sea; its the other way round, although water molecules can also scatter the blue light, which gives the intense blue colour to ice, if we look down a crevasse in a glacier.

Answer 2

It's actually the opposite of what KennyB said. The sky appears blue because the nitrogen and oxygen molecules in the air have approximately the same diameter as the wavelength of blue light. This means the blue light is scattered, making it come from all directions in the sky, rather than just directly from the point in the sky where the sun is. This also explains why the sun and moon rise orange (i.e. all of the blue wavelengths are scattered before they reach the observer). If all the other wavelengths were scattered, as KennyB said, the sky would have an orange hue instead.

BTW, if you look at Kenny's equation, it would seem that smaller values of lambda (wavelength) would increase the scattering effect...

Answer 3

the sky is blue due to the varied dust particles in the sky and since light consists of many colors , blue is the color that is visible due to its wavelength, compared to the other colours that usually show in a rainbow.

Answer 4

The light from the sun is scattered by water vapour in the air and the blue end of the spectrum reflects from the water droplets and dust.

Answer 5

due to the oxygen content in it. the oxygen in the atmosphere at 20.8 percent gives it the blue color.