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When the sun rises fully, the sky's colour is blue. Then why the colour of the sky has many colours during sunrise and sunset?
The colors of the sky are created because the atmosphere between the sun and the earth consists of many different particles and chemicals. The sky directly surrounding the earth though, mainly consists of nitrogen and oxygen molecules as well as the dust and pollution kicked up by humans and animals on the earth's surface. So, when the light hits these particles it is broken up and the different wavelengths are scattered in different directions. This process is called scattering. So with our atmosphere the sky surrounding the earth would be black and only lit up by the white light of the sun.
The wavelength of blue light is very small and can be broken up about ten times more than red light because red light has almost double the wavelength of blue light. So, blue light is scattered in more directions than the shorter wavelengths when it comes in contact with the nitrogen and oxygen molecules. Therefore, blue is the light that enters our eye.At dusk and dawn the colors of the sky change and the first portion of the visible spectrum is what appears to the viewer. During these times of the day the sun is positioned at a different angle to the earth than during the normal daytime. Because of this angle, the longer wavelengths are the ones that reach the eye. The blue and other shorter wavelengths are scattered millions of times and do not reach the viewer. When the sun does not shine directly on a certain portion of the earth there are more gas molecules between the viewer and the sun. Therefore, the normal blue color of he sky is no longer visible because the short wavelengths of blue and green are scattered millions of times and do not reach the viewer. Therefore the longer wavelengths that couldn't be scattered as many times are able to now hit the viewer in a more direct way.


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