WHY IS THE SKY BLUE?



Yes, why is the sky blue? Yet another first class question you can add to the list of:

'...questions I know my child will ask me as they grow up, which I probably won't know the answer to unless I make an effort now...'

Well look no more the answer is as follows:

The blue colour of the sky is due to Rayleigh scattering. The light from the sun looks white but really it is made up of all off the colour of the rainbow this consists of Red, Orange, Yellow, Green, Blue, Indigo and Violet.

Light energy travels in waves and blue tends to have shorter waves compared to the longer waves of red and the other colors in between the two. All of these light waves travel in a straight line unless it is intercepted by these things; light is either reflected (mirror),  bent (prism) or scattered due to the very small molecules found in the atmosphere.

As sunlight passes through the atmosphere, most of the longer wavelengths of light - that would be the red, orange, and yellow light - pass straight through with out being reflected, bent or scattered.

However, much of the shorter wavelength light  - blue, violet and indigo, is absorbed by the gas molecules which make up the air in the atmosphere.. The absorbed blue light is then radiated in different directions, becoming scattered throughout the sky. Whichever direction you look, some of this scattered blue light reaches you, and since you see the blue light from everywhere overhead, the sky looks blue.

Furthermore, as you look closer to the horizon, the sky appears much paler in color. In order to reach you, the scattered blue light must pass through much more air. This means that more of it gets scattered away in other directions. Less blue light manages to reach your eyes making the colour of the sky near the horizon appears paler or white.

For related articles click onto:
WHERE DOES THE WIND COME FROM?
WHY IS THE SKY BLUE?
WHY IS THE SEA BLUE?

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