Wednesday, January 8, 2014

Look, up in the sky: It's a sun dog!

The "mock sun," or sun dog, can be seen to the left of the actual sun. Photo by Woody Hickcox.

Even on an icy, cold day, when many people are just focused on trying to stay warm, Woody Hickcox takes the time to scan the outdoors and look for gems of natural beauty. That’s why he noticed the sun dog hovering amid the cirrus clouds over the Emory campus last Tuesday around 4 pm. He snapped the above photo from the 5th-floor patio of the Math and Science Center.

“They’re fairly common, if you keep your eyes out for them,” says Hickcox, a senior lecturer in Environmental Studies.

Sun dogs are atmospheric phenomenon caused by the refraction of light from hexagonal ice crystals, called diamond dust, that drift in the air at low levels. They may appear as a colored patch of light on one side of the sun, and can also include a luminous halo or arc.

"Back in the day, sun dogs were considered omens, like comets," says Hickcox. The above photo was taken at Stonehenge by Tim Daw (via Wikipedia Commons).

Here’s a link to a fuller explanation of sun dogs (known as parhelia to meteo-nerds).

Hickcox says his favorite sun-dog sighting occurred in the early 1980s, as he was driving with his family across Alabama. “It was one of those days when the sky was lit up with just about every optical phenomenon,” he recalls. “There were really good examples of sun dogs, halos and parhelic arcs. We pulled to the side of the road and just looked at the sky.”

Hickcox has taught meteorology at Emory for more than 30 years and next fall will teach a class on climate change. He invites those who are interested in the sky and optical phenomenon to drop by the department and look through some of the books he has collected on the topic, including striking photographs.

“The day-time sky is full of amazing and weird sights, not just sun dogs,” Hickcox says. “You just have to know what to look for and when.”

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