CBSE Class 10 Answered

When the sun is high in the sky, it looks white.  That’s because all visible wavelengths (or all colors) of light reach our eyes, and all colors add up to white.  As the sun sets, its light travels through the atmosphere at a much lower angle, so the sun shines through the lower atmosphere which contains dust, salt, smoke and pollution.   These particles scatter away some of the shorter wavelengths of light (the violets and blues), leaving only the longer wavelengths (the oranges and reds.) 

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