Here’s a look at the science behind B.C.’s rare purple sunrise

Many residents across the county woke up to a rare sight Friday morning: a purple sunrise.

Why did this happen? First, a quick explanation of why our eyes see certain colors during sunrise and sunset.

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The sun rises in purple on January 14, 2021.

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The sun rises in purple on January 14, 2021.

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The sun rises in purple on January 14, 2021.

When visible light passes through the atmosphere, tiny particles cause certain wavelengths or colors to scatter in the light spectrum. The further the distance, as at sunrise and sunset when the sun is low on the horizon, the greater the scattering of colors.

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Violet and blue have the shortest wavelengths so they are more easily scattered. The remaining colors that are able to reach our eyes are those with longer wavelengths such as orange and red.

The exact color we see depends on how far away from the sun is and the amount of particles in the atmosphere such as dust, pollution and water droplets.

If the sunrise or sunset is purple, cloud cover must be present.

Pink wavelengths, resulting from sunrise or sunset, create an optical illusion as they reflect off the base of the cloud.

However, when these clouds are dark or the sky behind the cloud is dark, this pink color can look like purple.

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The sun rises in purple on January 14, 2021.

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The sun rises in purple on January 14, 2021.

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