WICHITA, Kan. (KSNW) -- For the past month, viewers have shared photos with KSN of sunsets with a prominent blue streak in the sky like the one pictured below, and they want to know exactly what it is. Crepuscular rays, or sunbeams as they are more commonly known, are one of the atmosphere's most photogenic optical phenomena. (Getty Images) These streaks are an optical illusion known as Crepuscular rays. They're typically caused by clouds partially blocking the sunlight, often right at or below the horizon, where they may not be visible to the naked eye. Dust, particulates, or wildfire smoke can make them much more prominent. Why is Kansas so windy? Mountains can also create Crepuscular rays. You have seen something very similar before, just likely from a different angle, like in the examples below: Sunset from T'Ghammar Hill in Gozo (Getty Images) Sun rays and clouds, sunbeams shining through cumulus clouds. Inspirational landscape for meditation. Stunning scene of beautiful natural phenomenon, charming nature landscape (Getty Images) Crepuscular comes from the Latin word crĕpuscŭlum, which means Twilight. Crepuscular rays are just one of many atmospheric optical phenomena. You can learn more about the different types from this page from Colorado State University.