I Can't Classify This Weird Sky Thing

Photo date: September 11, 2015. Photographer: Mark Mahin.

The photo below shows a weird-looking thing I photographed in the sky last night. It looks like nothing I have previously photographed.

Below is the larger photo from which this photo was cropped.

There was no fog, mist, rain or precipitation on this night. The air quality listed on airnow.gov was "good," with a rating of 33.