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Anonymous
>>256446 The normal gasses in the Earth's atmosphere are nitrogen and oxygen, which scatter blue light. Hence the sky is blue when the sun is directly overhead, as the oxygen and nitrogen are scattering the blue light, making the sky blue.
When the sun is at the horizon, at dawn or dusk, the sky appears red because the dust and other particles in the lower atmosphere scatter red light more effectively than the nitrogen and oxygen scatter blue light, making the sky red at the horizon, and progressively darker/bluer as you look up.
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