A quick thanks to Clark for sending in the idea for this post. He says, “The other day I saw this strange light in the south… not a rainbow… lasted about 6 minutes only…..?” A very good question indeed. This is actually known as a circumhorizontal arc. According to Victoria Gillman at National Geographic, “…it is caused by light passing through wispy, high-altitude cirrus clouds. The sight occurs only when the sun is very high in the sky (more than 58° above the horizon)… [T]he hexagonal ice crystals that make up cirrus clouds must be shaped like thick plates with their faces parallel to the ground.
When light enters through a vertical side face of such an ice crystal and leaves from the bottom face, it refracts, or bends, in the same way that light passes through a prism. If a cirrus’s crystals are aligned just right, the whole cloud lights up in a spectrum of colors.”
So no, it wasn’t a UFO or some anomaly. It’s a real, explainable phenomenon. Courtesy of mother nature and the unique chemical/physical makeup of earths atmosphere.
wow & here I thought it could be space-invaders. seriously though, it is a striking image in the sky. How often does it occur?
Posted by ron | June 22, 2011, 7:13 amWell, normally if there’s a thin cirrus layer in the sky… and the sun has to be higher than 58*. Happens more than people realize, they just don’t pay attention most of the time.
Posted by spinjunkey | June 22, 2011, 7:55 am