Why is the Sky Blue?

I am going to nerd out this morning to answer this question....recently raised by a family member.

Everyone knows that sunlight is composed of all the primary colors. Think about the famous Pink Floyd album cover for Dark Side of the Moon or seeing a rainbow during a storm.

The light separates into its components because each color has a different wavelength. Think about permed hair to describe wavelength. A tight perm with lots of curls close together has a short wavelength. A perm with long, wavy curls has a long wavelength. Blue light has the shortest wavelength and red light the longest. All the other colors are in between. It just happens that short wavelengths (blue) are the easiest to separate out of light. Long wavelengths (red) are much harder to separate.

Finally, we all know the atmosphere is full of particles....some good (ice, water drops) , some bad (air pollution). These particles act like a prism and scatter the light. The angle of the sun when it is directly overhead allows sunlight to pass through only a few particles in the atmosphere. This causes the short wavelength blue light to scatter and be seen by us (why the sky is blue) but the longer wavelength yellow and red light does not scatter and penetrates to the ground.

So, if I provided a good explanation, you should be able to extend my logic to explain why sunsets are red.

Final note: Yes global warming is occurring....no doubt about that. However, we should become very worried if the sky turns green!