Why is the sky blue?

Answer 1

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The atmosphere is the mixture of gas molecules and other materials surrounding the earth. It is made mostly of the gases nitrogen (78%), and oxygen (21%). Argon gas and water (in the form of vapor, droplets and ice crystals) are the next most common things. There are also small amounts of other gases, plus many small solid particles, like dust, soot and ashes, pollen, and salt from the oceans.

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 you look closer to the horizon, the sky appears much paler in color. To reach you, the scattered blue light must pass through more air. Some of it gets scattered away again in other directions. Less blue light reaches your eyes. The color of the sky near the horizon appears paler or white.

Source(s):

http://www.sciencemadesimple.com/sky_blu…

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Asker's Comment:

good job? although there were two of the same answers yours is more science loaded.

Ben

Answer 2

Sunlight is a mix of all the colours of the rainbow. Light is a spectrum of light of different wavelengths, from the shorter "blue" to the longer "red" wavelengths.

When sunlight enters the atmosphere, the molecules in the air are the right size to "scatter" the blue wavelengths of the sunlight, which sort of "paints" the sky blue.

The reason the sun appears yellow to us is because some of the blue light has been removed by the atmosphere so there is less blue in the sunlight that reaches the surface (white sunlight minus some blue makes yellow sunlight).

Answer 3

Would you believe you are the 5471st person to ask that question? The answer is still Rayleigh scattering. Just type "why is the sky blue" into the "Search for questions" box above and check some of the answers.

Answer 4

reflection of the worlds bodies of water

Answer 5

This question has been asked over 5000 times, and I've prepared a simple answer, without too much science:

The correct answer is that the blue light is scattered by the air molecules in the atmosphere (referred to as Rayleigh scattering). The blue wavelength is scattered more, because the scatteing effect increases with the inverse of the fourth power of the incident wavelength.

OK, but I've known science graduates who don't understand what this means.
Here's my attempt at an answer without too much 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 strikes the molecules and is absorbed, causing the molecules to vibrate and give off, or 're-emit' the light. It's not the same as reflection, but the effect is similar. The molecules in the air are much smaller than the wavelength of visible light, but 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 the blue colour of the sea is mostly caused by the water molecules scattering the blue light, in a similar way. This effect is even stronger with ice; which results in the intense blue colour we see if we look down a crevasse in a glacier, or down a hole in the snow made by a ski stock..

For a complete, scientific explqanation, look up 'blue sky' in Wikipedia.

Answer 6

Because the sun is yellow and the grass is green. Yellow and green make blue. :)

Honestly there is a scientific answer, I just can't remember it. I think it has something to do with light refraction or something.

Google it!

Answer 7

Because thats how God created it silly.
Just kidding.. umm.. I think the reason why the sky is blue because of the atmospher above the (sky) which is outer space. Thats dark. But with the clouds and the climate it appears to be blue.
I hope this answered your question.

---opinion