- The atmosphere of Earth is made up of particles that filters white light.
- When the sun is overhead, the sky appears blue because the light is filtered, allowing the short wavelengths in the color specturm to be visible.
- When the sun is setting or raising, the light have to travel a further distance. Therefore it is the thickest amount of atmosphere the light have to pass through than at any other time during the day.
- This causes the short wavelengths to become scattered and deflected as the rays pass across the curved surface of earth.
- The sky is then slowly illuminated with longer light waves; yellow, orange and red. Sunrise are usually less intense because the air particles settle during the night.
- Under certain conditions, like after heavy rain, the sunsets can be bluer whereas in polluted cities or low lying cloud, they often become redder. It all depends on the density of air particles and distance the light have to travel.
- The thicker the atmosphere the deeper the red. Thinner atmostphere will produce orange, then even thinner, golds and finally yellows.
- The red light sometimes strikes the underside of the clouds directly overhead and turns them red, yellow and orange depending on the wave lengths of light that have managed to penetrate the earth's atmosphere.
-Before the sun completely sets, the light travels up the atmosphere, there is less particles there. Which is why, you can still see some blues.
U can read more about the theory below.