why is the sky blue?

Answer 1

Defraction of the sun's radiation into the atmosphere. Note that the more blue the sky, the more yellow the sun appears to be. If the sun appears more white, the sky is less blue. The blue light is defracted out of the sunlight and leaves the sun a yellow color.
-Good question.

Answer 2

This has been asked and answered numerous times...

http://answers.yahoo.com/search/search_result;_ylt=Ap_pjE49xJpS02Uc6cmDid0ezKIX?p=why+is+the+sky+blue%3F

THE SHORT EXPLANATION:

A clear cloudless day-time sky is blue because molecules in the air scatter blue light from the sun more than they scatter red light.

THE LONG TECHNICAL DETAILS:

The sky is blue due to Rayleigh scattering. This effect was actually first observed and described by John Tyndall, and a only few years later was explored in more detail by Lord Rayleigh.

Rayleigh scattering is the scattering of light by particles. In the case of the sky, these particles are the molecules of air, themselves, and not dust or water vapor as is often proferred. The scattering depends on the wavelength of the light. Light towards the violet end of the spectrum scatters more than light at the red end. Sunlight is scattered throughout the sky and causes it to appear blue to an observer on the ground. The reason the sky doesn't appear violet to us has to do with the sensetivity of the cones in the human eye.

Just as the blue light gets scattered, red light from the sun travels farther, which is why the sun appears yellowish-orangish. In space the sun appears noticeably more blue. Space is black because there are almost no particles to scatter light.

Answer 3

This exact same question has been asked about 1,000 times before right here on Yahoo! Answers, not to mention in thousands of other places it's easy to find on Google.

Why not take two seconds to look up the answer rather than bothering other people to give you the same answer everyone else gets over and over again?

Answer 4

Rayleigh scattering.

The amount of scattering which light undergoes when passing through the atmosphere is proportional to the inverse fourth power of its wavelength. The upshot of which is that more blue light is scattered (and ends up in your eye) than longer wavelengths.

Tadaaa!
Cheers.

Answer 5

The sky is blue Cuz the grass is green and the sun is yellow. So yellow and green makes BLUE!!

Answer 6

because of different molecules in the atmosphere, and also ozone gas, the suns rays refract off of these molucules, making the illusion of a blue sky.

Answer 7

the sky is not actually blue. it's black. we are too far away from it that we see it blue. otherwise it is black.

Answer 8

It's the reflection off the water

Answer 9

As Lucy has said, "Because it's not purple"

Answer 10

Because it is mostly water vapor.