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