Why does the sky on the horizon turn red or pink in the evenings?
As the sun begins to set at the end of the day, the sun’s rays which reach our eyes are farther away and must pass through a thicker layer of the atmosphere than when sun is directly overhead. As it does so, molecules in the earth’s atmosphere absorb more of the radiation, but it gets absorbed preferentially. The shorter lightwaves of the visible light spectrum, the greens and blues, get absorbed, while the longer red rays are able to penetrate. Therefore, red is the colour we see!
As the sun begins to set at the end of the day, the sun’s rays which reach our eyes must pass through a thicker layer of the atmosphere than when sun is directly overhead. When this happens, molecules in the earth’s atmosphere absorb more of the radiation, but it gets absorbed preferentially. The shorter light waves of the visible light spectrum, the greens and blues, get absorbed, while the longer red rays are able to penetrate. Therefore, red is the colour we see. Dust and smoke particles can help to enhance the scattering of sunlight creating even more vivid red skies at dusk.
