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How Sun dogs appear in the sky | Hey Ray

Hey Ray: How Sun Dogs form in the sky
Hey Ray: How Sun Dogs form in the sky 01:59

PITTSBURGH (KDKA) - Dogs are great. Some consider them man's best friend, and who am I to argue? Not all dogs are created equal though.

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A Sun dog appears in the sky.  Ray Petelin

The topic today is more about a weather type of dog that doesn't look like a dog at all... Sun dogs. You may have noticed these as a tiny rainbow spot in the sky. I get questions about these all the time. For Sun dogs to appear, you need sunshine and ice crystals suspended in the atmosphere.

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A larger view of a Sun dog appearing over wintery terrain.  Ray Petelin

Sun dogs typically appear to the right or left of the Sun. You can also have a Sun dog on the right and left at the same time, about 22 degrees to the right or left of the Sun if you want to be more precise! You may remember that amount of 22 degrees from a previous Hey Ray about halos. The hexagonal ice crystals that refract light to create Sun and Moon halos are present when Sun dogs are created, too.

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A diagram of how Sun dogs form with light and ice crystals. Ray Petelin

Those tiny ice crystals refract the Sun's light to make the rainbow-effect happen. Typically, the colors go from red closest to the Sun, to blue on the outside of the Sun dog. According to Georgia State University, the red appears sharper and closer to the Sun with light refracting at an angle of 21.54 degrees, and the outer edge is blue with light refracting at an angle of 22.37 degrees. You will usually see a Sun dog when the Sun is lower in the sky, so typically in the morning or evening.

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A bright blue sky with a large Sun dog. Ray Petelin

Just like your dogs, Sun dogs have some different names. The National Weather Service said they are also known as "mock suns" or "parhelia" which means "with the Sun".

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