Here's Why the Sky Over New England Turned Such Gorgeous Colors Monday

To understand the light show we got at sunset, you need to know about how light itself works, and how the atmosphere bends and scatters it

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After dreary skies and rain on Monday, New Englanders were treated to a beautiful sunset as a front passed through.

The threatening skies turned beautiful hues of yellow, deep orange, red and pink — and that's not even touching on the rainbow that many people saw!



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Stunning Rainbow Graces Boston's Skyline

Many people have been wondering what caused such a stunning light show. It's all due to the visible light spectrum and light scattering.

The sun produces what's known as white light, a combination of all of the colors from the visible light spectrum in the range of colors we see: violet, indigo, blue, green, yellow, orange and red.

White light travels at different wavelengths and, as its energy decreases or increases the hue (or color) the light gives off changes. The shorter wavelength of light produces violets and blue hues, and they are scattered more quickly than the longer wavelengths, yellow, orange and red. That leaves the resultant oranges, reds and pinks that we saw Monday night.

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It can be taken a step further, too — as those light particles scatter, or bounce off of, different gases, pollutants and particles in the atmosphere, they get an even deeper hue, through a combination of phenomena called Rayleigh scattering and Mie scattering.

Named after Lord Rayleigh, a 19th century physical scientist, Rayleigh scattering is the scattering of light by small particles, generally less than 1/15th of the wavelength of light. It’s what gives the atmosphere the blue hue we usually see. Mie scattering occurs when light is scattered by particles of a larger size.

Monday's sunset was a really good combination of both.

At sunset, sunlight enters the atmosphere at an angle and refracts, or bends. This lengthens the path the light has to travel, causing even more Rayleigh scattering. The clouds took the color of sunlight they received from the Rayleigh scattering. The resultant color we see is due to Mie scattering, which scatters the remaining wavelength colors equally.

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