WGNO

Why the sky will be turning a richer shade of blue

(KXMB) — As the seasons change, we expect the temperatures and weather patterns to change too. But did you know the color of the sky will also change?

In the spring and summer, you’re more likely going to see a light blue sky. Sometimes, it’s kind of a milky appearance, and some days, it can be so light it almost looks white. But in the fall and winter, you’re more likely to see richer shades of blue. That rich blue color is especially pronounced if you live somewhere you’ll be seeing snow on the ground.


A side-by-side comparison shows how sky color can change from season to season. (Photos: Getty Images)

The transition can be subtle over several months, so it can be hard to notice the change as it happens.

The seasonal differences in sky color come down to the composition of the atmosphere combined with where the sun is in the sky.

The summer sky has more water vapor. The warmer the air, the more water it can hold, so the sky has larger water droplets. Those larger water droplets scatter light into a milky white haze. The sun is also at a higher angle, so there is more scattering of light. Our eyes perceive this as a lighter shade of blue.

In the winter, the air is typically drier. It’s colder, so it doesn’t have the ability to hold much moisture. That means the water droplets that are in the air are much smaller. That, combined with lower sun angles, means we have a limited amount of light scattering, which leads us to perceive more deep blues and purples.

Differences in temperature, humidity and the angle of the sun cause our eyes to perceive the sky as a richer shade of blue in the winter. (Photos: Getty Images)

This same principle applies to sunrises and sunsets and how our eyes perceive with golden hues. The longer the scattering of light, the more oranges and reds your eyes pick up.