Sun dogs are often seen in our region in cold morning air following a snowstorm. Many people, therefore, associate sun dogs with cold air, even thinking that one causes the other. However, this is not quite right. Sun dogs are a refraction of sunlight caused by ice crystals in the air. The crystals work sort of like raindrops, but with different mechanics, to bend and separate the light into colors.
The ice crystals that caused the sun dogs Monday morning were actually windblown snowflakes suspended in the air following the Sunday night blizzard. Thin clouds can also cause sun dogs if the clouds are made of ice. This method can produce sun dogs in hot summer weather but summer sun dogs are not as bright because clouds made of ice are much higher up and so farther away. In extremely cold weather, water vapor will spontaneously freeze and so very cold weather is one cause of sun dogs, but not the only one.
