Why are some sunset skies bright orange and red, while others are not?
Sunsets appear orange and red because of the way sunlight is scattered as it passes through the Earth’s atmosphere. Sunlight, like all forms of radiation, travels as waves. The wavelengths at which visible light travels range from about 0.4 micrometers (or microns; 1 micrometer = 1 millionth of a meter) to about 0.7 micrometers. At the short end of this range are the blue and violet colors, while the oranges and reds have longer wavelengths. During the day, air molecules in the atmosphere scatter incoming sunlight in different directions — a process known as Rayleigh scattering (named for Lord Rayleigh, an English physicist and mathematician who first described the effect.) Since Rayleigh scattering occurs more at the lower wavelengths at which visible light occurs, the blue portion of sunlight is more effectively scattered and the sky appears blue on a cloudless day. During sunrise and sunset, however, sunlight must pass through more of the Earth’s atmosphere, allowing more scatterin
Sunsets appear orange and red because of the way sunlight is scattered as it passes through the Earth’s atmosphere. Sunlight, like all forms of radiation, travels as waves. The wavelengths at which visible light travels range from about 0.4 micrometers (or microns; 1 micrometer = 1 millionth of a meter) to about 0.7 micrometers. At the short end of this range are the blue and violet colors, while the oranges and reds have longer wavelengths. During the day, air molecules in the atmosphere scatter incoming sunlight in different directions — a process known as Rayleigh scattering (named for Lord Rayleigh, an English physicist and mathematician who first described the effect.) Since Rayleigh scattering occurs more at the lower wavelengths at which visible light occurs, the blue portion of sunlight is more effectively scattered and the sky appears blue on a cloudless day. During sunrise and sunset, however, sunlight must pass through more of the Earth’s atmosphere, allowing more scatterin
