The following 4 periods likely illustrate microphysics of sublimating cirrus. The aircraft was quite close to cloud base.
DATA FOR 25 November 91:
15_46_05 UTC 15_47_17 UTC 15_49_30 UTC 15_49_48 UTC
15_46_05 UTC
15_47_17 UTC
15_49_30 UTC
15_49_48 UTC
Graphical Representation of Sublimating Cirrus
(click on data points for further information)