WeatherTalk: Sun dogs are not always a sign of cold weather

The sun dogs Monday morning were caused by snowflakes suspended in the air following the Sunday night blizzard.

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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.

John Wheeler is Chief Meteorologist for WDAY, a position he has had since May of 1985. Wheeler grew up in the South, in Louisiana and Alabama, and cites his family's move to the Midwest as important to developing his fascination with weather and climate. Wheeler lived in Wisconsin and Iowa as a teenager. He attended Iowa State University and achieved a B.S. degree in Meteorology in 1984. Wheeler worked about a year at WOI-TV in central Iowa before moving to Fargo and WDAY..
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