why is the colour of sky blue?

Answer 1

reflection of the sun's light through the many layers of the atmosphere

Answer 2

This is a commonly asked question. and the correct answer is that the molecules in the air scatter the blue wavelength of the spectrum (known as the Tyndall effect, or Rayleigh scattering)..That is fine, but I know science graduates who still don't understand this explanation.

Here is my explanation, with a limited amount of physics involved: (I also improved my answer, thanks to an answer given by Yahoo member Einstein a few weeks ago)

I think most people know that white light is made up of a spectrum of different colours, which can be broken down with a prism (or in a rainbow), showing a range of different colours, from red to blue. Technically, the red light has the longer wavelength, and the blue the shorter wavelegth (there are other wavelengths such as infrared and ultraviolet that our eyes cannot see).

When the light passes through the atmosphere, the sunlight reacts with the air molecules, causing them to oscillate and emit radiation of the same frequency (the same colour) as the incoming sunlight, but the emitted light is spread over all directions (called scattering). Because the blue wavelengths are the shortest and most energetic, they react much more with the air particles, and are scattered more, wheras the red and yellow wavelengths tend to pass right through.

That is why, when we look up at the sky, the sky seems blue, and the blue colour seems to be coming from all directions. We are seeing that scattered light, which is made up much more of the blue part of the spectrum, rather than the red and yellow. When the light reaches us on the ground, we see the combined effect of the red and yellow wavelength light passing straight though, mixed with the blue light reaching us from the sky.

If you see a sun beam passing through a narrow space into a dark room (eg through a slit in a blind) it will look more yellow, because it lacks the scattered blue part of the spectrum.

That is a simplified answer, and not scientifically accurate, but is the best explanation I can think of, without using too much physics.
I am indebted to member Einstein, for putting me straight on this, as my original answer was much too simple.

Answer 3

That guy above is evil. His answer is too long and complicated and I bet you don't like it for that reason. haha!

The sky is blue due to the scattering of light. The white light comes from the sun and is split into different colors. The small particles (smaller than the width of a wavelength of light) in the air do the refracting (splitting). We see blue because blue light travels faster then other wavelengths (colors) of light.

Answer 4

Each color of light travels using different wave lengths. Our eyes interpret these wave lengths as individual colors. In the atmosphere colors separate from the sunlight and different times, blue being one of the last colors to break off and letting us see the sky as blue most of the time. Reds and Yellows and Oranges break off sooner and that is why when the sun is setting you see those colors on the horizon, much closer to the sun, since they separated first.

Answer 5

well because god thought it would look with all the colours of the world