Saturday, January 4, 2003, at about 11:30 AM, there was an atmospheric condition that many of us have seen before. It was a light display called sundogs. Sundogs are colorful bursts of light that appear on either side of the sun. They generally occur when the sun is low in the winter sky, at either sunrise or sunset.
Flat ice crystals form in hexagonal shapes, similar to stop signs. Their flat faces are horizontally oriented and refract the sunlight. The white light is bent 22 degrees before reaching our eyes and the resulting sundog shows up with the color red closest to the sun and the color blue on the outside.
At 11:30 AM, the sun was high in the sky and the sundogs were accompanied by a halo circling the sun. Halos surrounding the sun or moon are indicative of slightly different forms of ice crystals. They form within high cirrus clouds about 30,000 feet. Instead of flat stop sign shapes, they are long hexagonal crystals resembling the shape of pencils. These pencil-shaped crystals tend to align themselves in a way that maximizes air resistance as they fall, producing halos. This halo is called a 47-degree circum-horizontal arc and is seen when the sun is high in the sky, as it was on Saturday, January 4th.