Before we can understand why the sky looks bluer in the fall, it's important to first know why the sky appears blue in the first place. The sun emits white light, and due to Rayleigh scattering (the scattering of light by air molecules), blue light ...

It's an age-old question and one that any meteorologist hears quite often. Why is the sky blue? It has to do with light waves and how they travel through our atmosphere. The light from our sun travels 93 million miles to reach the surface of the Earth.

Look up! The sky takes on an extra-blue hue in the fall, because of low humidity and an increased amount of Rayleigh scattering.