By Grace Gaard
The sky. Every day it changes with new colors and patterns and clouds. And in the winter, when the air has that quiet bite to it, there is beauty you might not find at other times of the year.
If you’ve stepped out into a cold winter evening just as the sun is dipping behind the horizon, you may have found your breath catching at the sight of the colors in the sky. Hazy purples and blues along the edges of the landscape. Fiery pink and red beams arcing across the clouds.
The vibrancy of these winter sunsets isn’t your imagination. There’s actual science to explain this fiery phenomenon.
The Why Behind the Colors in the Sky
Let’s start with the sun. We all know that the sun shares its warmth and light with us throughout the year. Each ray of that light contains all the colors of the rainbow within it.
As these rays of sunlight travel through the Earth’s atmosphere, they come into contact with various molecules, such as nitrogen, oxygen and other particles, in the air.
These “collisions” cause the light rays to ricochet in unique ways depending on the color and its wavelength. This is called Rayleigh scattering, and the wavelength essentially determines how far the color needs to go for us humans to be able to see it. This is why not all colors will reach the ground in the same concentrations.
When blue and violet light come into contact with the Earth’s atmosphere, their light scatters more readily in all directions above us leading to lower concentrations of blue and violet light reaching Earth. This is why our sky looks blue and the Earth appears sheltered by a blue dome from certain angles.
When the sun is setting, our planet is rotating away from the sun, meaning light must travel even farther to reach our eyes. Coming into contact with more molecules in the atmosphere leaves blue and violet light scattering away from our eyes, while colors like red, orange, pink and gold steal the show.
Ingredients for a Colorful Winter Sunset
Understanding how light reaches the Earth and what colors we see helps us when thinking about why the sky lights up even more brightly in the winter months.
Nebraska’s outstanding winter skies are created by a few key elements:
- The weather
- Nebraska’s location in the Midwest
- The angle of the Earth
In winter, the weather in Nebraska can be unpredictable. One day it’s sunny and 50 degrees, and the next day, temperatures might plummet to the 20s. Don’t even get me started on the wind!
But as we head into December, the consistency of those cooler temperatures evens out, and by January, the air is dry and cold. This lower humidity, combined with less dust and pollen particles compared to warmer days produces a crisp sky with minimal barriers for light and color to pass through.
We have pretty clean air in the Midwest. When a polar vortex comes through, icy clean air makes its way southward. That clear atmosphere means that light has less barriers and more colors will reach our eyes.
Finally, the angle at which the sun sets is different in the winter, especially near the winter solstice. During this time of year, the Earth’s Northern Hemisphere is tilted away from the sun. Though winter nights come sooner and last longer, this tilt of the Earth results in rays of sun stretching out across the sky longer. Essentially, the setting of the sun lingers, which adds to drawn-out sunsets.
One last feature that makes these sunsets even better? Clouds.
With the right blend of temperature gradients and cloudy systems moving off to our west, these winter skies can become the perfect tapestry of texture and light, a colorful display that sends us into the dark night with the warmth of those colors in mind.
See for Yourself
If you’d like to chase a colorful winter sky, this event can be predicted to a certain degree. A little research into when the sun sets in your location, humidity levels (look for low) and cloud cover can indicate if the conditions will be just right.
However, if research doesn’t appeal, who doesn’t love walking out to the surprise of a saturated sky as they leave work or the grocery store? You know all the best sunsets tend to happen when you’re in a parking lot.
On these long, dark nights, I hope you’ll find solace in the sky. Though the weather is cold and the days are short, the gift of a winter sunset can carry us through.