Originally posted by AKWarp
"Water, the sky is blue because of the sun light hitting the water in the air. This is the same reason earth is called the blue planet. Which could raise a simular question as to why does the sky turn red/orange in the evening? Well I'm glad you asked, it's the the sun light reflecking off the dust in the air. The angle of the light show us the orange/red part of the spectrum. The same effect can be seen by passing light through a prizm which breaks the light into all colors. "
Nope, wrong answer. Water or dust in the air is not it. It has to do with the wavelength of the light and it's absorption and scattering not by water or dust, but by all the molecules in the atmosphere (the gas molecules, like oxygen, nitrogen, etc).
Blue light, being a shorter wavelength, is scattered more easily, thus when the sun is out, you see blue sky because blue light waves are scattered and bounced all around. Look toward the horizon, it is paler than directly above you because of the distance. Light traveling to you from the horizon has further to go, the short wave lengths are scattered and absorbed more, thus it is paler.
The sky is orange or red in the evening because the sun is low on the horizon and the light has a further distance to travel through the atmosphere. The long wavelength oranges and reds make it through, but the blues do not.
Your right and your wrong. Dust and particles do have a bearing on the colors.
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WHY IS THE SKY BLUE?
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.
WHY IS THE SUNSET RED?
As the sun begins to set, the light must travel farther through the atmosphere before it gets to you. More of the light is reflected and scattered. As less reaches you directly, the sun appears less bright. The color of the sun itself appears to change, first to orange and then to red. This is because even more of the short wavelength blues and greens are now scattered. Only the longer wavelengths are left in the direct beam that reaches your eyes.
The sky around the setting sun may take on many colors.
The most spectacular shows occur when the air contains many small particles of dust or water. These particles reflect light in all directions. Then, as some of the light heads towards you, different amounts of the shorter wavelength colors are scattered out. You see the longer wavelengths, and the sky appears red, pink or orange.
