The sight of a mixture of reds, oranges, and other colors across the sky at day’s end. That’s the look of a serene sunset. But not all sunsets are equal. What are the ingredients that make up the artistic masterpiece of hues and colors at sunset, and why do we see the colors that we see?

 

 

The colors that we see are determined by the wavelength of light that can get through from below the horizon. Recall the visible light spectrum, where each color has a different wavelength; red being the longest and violet being the shortest. These wavelengths matter because, just as ultraviolet (UV) waves are broken up naturally, the short-wavelength colors are also broken up by the time the sun sets. This is why throughout the sunset timeline, the sky goes from a yellowish hue to orange, and finally red.

 

 

At the surface, it would make sense if there was little-to-no cloud cover to allow for uninterrupted color. But as it turns out, cloud cover serves as another place to intercept sunlight. This means that hues of red, pink, and orange can line the bottoms of clouds and make the overall scene more vivid. It is important, though, that there aren’t too many clouds; a surplus of coverage will lead the setting sun to be blocked entirely. A cloud cover of around 50% is generally considered the best ratio to have. It is important that these clouds do not interfere with the horizon, where they can serve to mute the color.

A cloud’s height also matters. If a cloud is too close to the ground, then the residual light will “overshoot” the bottom of the cloud as it goes further below the horizon. Typically, the higher and thinner the cloud, the better and longer the light will "stick" on the cloud.

Timing also matters when trying to capture a stunning sunset scene. Typically, colors can be seen in a 45-minute window around sunset, with the last, deepest reds fading from the highest clouds around 30 minutes after the sun dips below the horizon. The sweet spot? Between 10-20 minutes after the sun has set, owing to the optimum balance between the type and amount of color.

The time of year also matters. While those looking to see a dazzling show of colors can do so at any point in the year, in our area, the most vivid sunsets specifically occur in the cooler months. This is due to prevailing weather patterns being drier, which allows for less cloud cover.

Speaking of a clean atmosphere, particle density in the air can also change how sunsets are viewed. Typically, a hazy evening enhances the amount of color, with the drawback of diluting the vividness. On nights like these, viewers would typically see a colorful sky without much contrast.

While there aren’t many resources available specifically for forecasting a beautiful sunset, this article details the biggest factors in creating a masterpiece in the sky. Understanding the day’s cloud coverage, moisture, and air quality will all be important in judging if the day’s sunset will be a magnificent one.

As always, if you do scope out a good sunset, make sure to take a photo and send it to us on the StormTracker 21 app!