FORT WAYNE, Ind. (WANE) — We get our fair share of beautiful sunrises and sunsets here in northeast Indiana and northwestern Ohio. The colors that we see are so much more than just a random phenomena, in fact, there’s a lot of science packed into it!

Our colorful morning and evening skies begin with incoming sunlight from the Sun. We’re able to see this incoming energy in the form of visible light. We see that here on Earth in the form of both sunlight and color.

However, the colors that we see are dependent on three different things: Wavelength, path length, and a process we call Scattering.

Wavelength

Wavelength refers to the distance from crest-to-crest or trough-to-trough of a wave.

Remember ROY-G-BIV from high school? Well, each color in the rainbow has a different wavelength. Colors like red and orange have the longest wavelengths while colors like blue, indigo, and violet have the shortest wavelengths.

colors-and-wavelengths
Notice how blue has the shortest wavelength and red has the longest wavelength

Path Length

Path length refers to the distance that the wave of sunlight has to travel in order to reach the surface of the Earth. Or, in this case, to be seen by the human eye.

The path length changes based on the time of day that it is. When the sun reaches its peak in the sky, the path length is the shortest. When the sun is rising or setting on the horizons, it has the longest path length.

path-length
The path length of incoming sunlight varies depending on the time of day.

While you might think it would be a straight path directly to Earth, it’s far from it. The incoming sunlight encounters obstacles on the way down. In fact, it encounters millions of tiny obstacles.

Scattering

This bring us to a process we call “Scattering” in the world of meteorology.

Our atmosphere is full of molecules like air, smoke, water vapor, and so much more. When the incoming sunlight collides with these molecules, it becomes “scattered” in nature and bounces off of it’s original path. However, some colors scatter out more than the others. Specifically, colors with shorter wavelengths (blue and violet) scatter out very easily because of how short their wavelengths are. This doesn’t mean that those colors completely disappear from the sky during the sunrise or sunset. They’re just so scattered at that time that the human eye doesn’t see it. Therefore, we’re left with the classic vibrant colors (red, orange, and even yellow) we know and love so well for our sunrises and sunsets!

Adding it all together!

By adding all three factors together, we get the colorful skies we know so well!

As our sun begins to set on the horizon, the incoming sunlight takes the longest path to get to the surface of the Earth and to get to the human eye. The blues and violets we know scatter out in the atmosphere, but the red and orange colors continue on and the human eye is able to see them because of their long wavelengths!

Science has a hand in almost everything here on Earth, some of which happen to be quite beautiful for us.

Next time you get to enjoy the sunrise or sunset, perhaps you can appreciate the science behind the colors we get to see.