Why are sunsets red and orange?

Photo by Shell Randall. The Tri-States saw an incredible sunset Sunday thanks to a process called rayleigh scattering.

The big story across the Tri-States Sunday was the vibrant sunset after a very dreary day.

Colorful sunsets, and sunrises for that matter, occur thanks to a process called Rayleigh (Ray-Lee) Scattering. Light emitted by the sun is white, made up of a rainbow of colors. That rainbow can be seen when dispersed by prisms (Pink Floyd's Dark Side of the Moon album cover) or raindrops, and that's how you get rainbows in the sky.

However, particles in the atmosphere like dust, smoke and other pollutants, can scatter the light.

As the sun gets close to the horizon, it has to go through more of the atmosphere. That prevents the shorter-wavelength light like the blues and greens to to make it all the way where the sun appears to be setting.

The longwave light, the reds and oranges, can get passed most of those particles, therefore that is the light you see.

On day's when you have a lot of smoke in the air from wildfires as an example, the smoke particles can also scatter the light. That's why you may see very strange colors at other random times of the day. This was the case across the Midwest two months ago due to large wildfires in the Pacific Northwest.

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