Good Question

Good Question: Why Is The Sky Blue?

SACRAMENTO (CBS13) ― When Professor Richard Zare looks at the sky, he sees the colors of the rainbow.

"You know, white light is a combination of colors of the spectrum- orange, yellow, green, blue, purple," says Zare.

And in his lab at Stanford, Zare's students use advanced lasers to learn how all those segment of light behave.

Basically, different colors travel in different wave lengths; waves are wider on the red side of the spectrum and narrower at the violet end. In the case of sunlight it's all very orderly until the different light waves collide with the earth's atmosphere and scatter across the sky at different rates.

It turns out that violet light is scattered much more than red light and that's why people say the sky is blue.

So, if that's the case, why doesn't the sky look purple?

The light from the sun isn't all of the same intensity in each color. The sun actually peaks in the green/yellow region like our region does and falls off when we go towards violet. And the less intensity on the violet side shifts the tint back just slightly and leaving the sky blue.

Viewer Kimberly from Rancho Cordova took this question one step further, asking why the clouds are white. The answer is: the water droplets or ice crystals in cloud scatter act like the gases in our atmosphere do. They scatter the light from the sun and look whitest when there's lot of sunlight.

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