There are colorful sunsets everywhere in the world, but the deserts and the tropics are particularly noted for the wonderful, bright colors of their sunsets. Why is that? Is it pollution? Is it cloud formations? Is it beings from other planets shining flashlights downward?
Of course, there is a scientific explanation. I'll try to keep it simple so that even I can understand it!
- Dust does not cause brilliant sunsets. If it did, certain cities like New York and Mexico City would be on top of the list, and they are not. Actually, clean air is best for the best sunsets.
- Sunlight is composed of a spectrum of colors that ranges from violet and blue at one end to orange and red on the other. At sunrise or sunset, sunlight takes a much longer path through the atmosphere than during the middle part of the day. More violet and blue light is scattered out of the beam along the way, and so the light which reaches the human eye early or late in the day is reddened. So the conclusion is that sunsets are red because the daytime sky is blue. (Please don't ask me why the sky is blue.)
- Pollution softens the sky's colors, because the particles of dust and dirt are scattered and are of varying sizes, so the wavelengths sunlight of light passing through the particles are mixed. This lets us see muted tones, more middle of the spectrum.
- The best sunsets occur when there are at least a few high clouds. Higher clouds are hit by the sun's rays before they pass through the lower atmosphere, where the air has more particles. So the bright reds and oranges are filtered through at the high cloud's level.
Sunset info obtained from the National Oceanic & Atmospheric Administration (NOAA).