Colour

[Factfinder]

Why is the sky blue? Are black and white classed as colours?

[Skids]

The blue colour 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 colour. 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 colour of the sky near the horizon appears paler or white.

In an artist's world black and white are colours. They can be used and mixed just like anyother tube of paint.

Scientifically, however, a white surface (like white paint)looks white because it is reflecting all wavelengths of light (so its not a colour but all colours), and a black surface looks black because it is absorbing all wavelengths of light (so it is no colour). Which is also why black things hold their heat better than white things.

[:Ace:]

Black and White are actually shades. For example a shade of Red can be Black after it has got SO dark. And a shade of Red can also be White after it has got SO light.