Ripples 11/28/19

Written by Jessica Johnsrud, Education Coordinatorphoto of a wintery sunrise

Early in the morning, I often walk along Lake Michigan to take in the sunrise. I enjoy this quiet time and like watching how quickly the colors of the sky change as the sun makes its appearance for the day. There have been some pretty dramatic sunrises, and sunsets, as of late. From pastel pinks, blues and yellows to intense indigos, fushias and fiery oranges, they have been incredibly stunning.

The sun’s rays contain all the colors of the visible light spectrum: red, orange, yellow, green, blue, indigo and violet. Perhaps your elementary school teacher taught you to remember the colors and the order by learning the acronym ROY G BIV. Together, all the colors appear as white light. Light energy travels in waves and each color has a different wavelength. Blue and violet light are shorter waves and red and orange are longer waves. This is observed when sunlight travels through a prism and the white light is separated into all of its colors.

As the sun’s light enters the atmosphere, it interacts with water and ice molecules in the clouds, and dust and other particulates in the air. These obstacles in the atmosphere deflect and diffuse the light waves. This is known as scattering.
Blue and violet have shorter wavelengths, so are scattered more easily than the other colors. This is why the sky appears blue on clear days.

In the morning and the evening, when the sun is low on the horizon, light rays must pass through more atmosphere. This means the blue and violet light scatters, but since the light has to travel further, blue and violet scatter out of the line of sight and become very faded. This leaves the longer wavelengths of the light spectrum, red, orange and yellow, visible and explains why sunsets and sunrises are often magnificent reds and oranges.  

Red has the longest wavelength of all visible light and is why the sun appears crimson when it’s on the horizon. The light has to travel through so much atmosphere, that all other colors are scattered and just red is visible to our eyes.
Sunrises and sunsets are a welcomed part of each day. For some people it may signify a new beginning, for others it’s a reminder to slow down. I like sunrises and sunsets because they are free and can be enjoyed by everyone.  

Photo taken by Jessica Johnsrud 

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