WRAL WeatherCenter Blog

Pummeling a Parhelia!

Posted April 13, 2010 10:21 a.m. EDT

This happened a while back, but i just ran across the video today and thought I'd refer others who might have missed it. Back on February 11th at around 10:23 am, NASA launched the Solar Dynamics Laboratory on an Atlas V booster. A layer of cirrus clouds decorated the sky at the time and was producing a nice sundog, or "parhelia," created when rays of sunlight are refracted through six-sided ice crystals that are preferentially oriented with the plates parallel to the ground.

In the linked videos, the rocket passes through the cloud layer near the sundog location, crates a mesmerizing series of shock waves flowing across the cloud layer, and in the process "extinguishes" the sundog by disrupting the orientation of the ice crystals that produce it.

The first video link is to a zoomed in version of the movie that includes a second time through in slow motion. The second video link is from the same video, but is longer and includes the entire launch sequence. I also included a link to more information about sundogs and one to the Solar Dynamics Observatory home page. Enjoy!