The sky is blue most of the time, but it can take on other colors and hues depending on several factors. Some of these factors are harmless and beautiful, while others may be indicative of severe weather phenomena. For example, the sky can turn yellow if there is an abundance of dust and moisture in the atmosphere or a coming storm.
Many people have been noticing the sky has turned a pale, dingy yellow color this evening in parts of Minnesota and North Dakota. While it isn't a good sign for anyone who has allergies, the phenomenon is actually quite interesting. The color change has been caused by thunderstorms brewing over the region.
While thunderstorms are usually most common in the late afternoon and early evening, they can also occur during the morning and the night. When they do, the resulting clouds often appear a yellowish-orange color due to the way light is reflected in them.
This is because the rays of sunlight that shine into the clouds from above get scattered and distorted as they travel through the atmosphere. Normally, shorter wavelengths like blues get scattered faster than longer wavelengths such as reds. But if there's a lot of dust in the air, more yellow wavelengths are reflected than blue ones.
When this occurs, the sun can look a lot more red than usual during sunsets and sunrises. The same process can cause the sky to turn yellow during the day as well, especially when there is a lot of dust in the air or if the temperature is high.