Subsun 'Tails'
   
Large images: Jerry Xiojin Zhu (site) near Chicago December '04. ©Jerry Xiojin Zhu, shown with permission.
Small image: Raymond L. Lee (site) during a descent into London, England June '97. ©Raymond L. Lee, shown with permission.

In both cases the aircraft was quite low. Each photographer took several images.

Subsuns are produced by reflection from the near horizontal faces of plate shaped ice crystals. The curved tails below the subsuns are unusual. Window scratches can produce similar effects but that is not the case in these images.

A possibility is that the tails are produced by crystals tilted from horizontal in the aircraft airstream.

There is a problem!   By measuring the angular length of the light streaks, knowing the camera shutter speed and estimating the airplane airspeed, the distance of the crystals producing the glints can be calculated. In these two separate cases they are 40-60m away. By comparison, the wingtip distance of a 737 (Lee's aircraft) is only 15m which somewhat rules out trailing wingtip vortices. The glinting crystals are well beyond the wingtips. The causes of the tails are uncertain.

Acknowledgements to Raymond Lee and Walter Tape for discussions and ideas.