Why is the sky blue?

So, the weather in Los Angeles finally changed from 84 and sunny to 79 and cloudy, which is drastic for LA. It’s funny how the city goes into disarray when there are some clouds in the sky and it’s interesting watching people’s mood fluctuate based upon sunlight exposure.

But as I was walking around outside I thought about the sky’s color and what causes it as one of my students asked me the other day. The answer is preferential scattering of light.

As white light enters the earth’s atmosphere it is broken down into its component parts, which is all of the colors of the rainbow. During the day then the blue light is “preferentially scattered,” or a better way to put it is that the blue light is chosen to be separated, and then this light becomes the background of the sky.

Then as the sun changes position throughout the day it goes closer and closer to the horizon and when it does so the light that’s chosen to be separated changes and it usually culminates with a purple-y or pinkish color at sunset.

So, next time you look up and see a pretty sunset to post on Instagram you’ll know why it’s that color 🙂

Cheers,

Hasan Ali

Blue Light