strange cloud formations

In a paper that is about to be published in the Bulletin of the American Meteorological Society, researchers Andrew Heymsfield, Patrick Kennedy, Steve Massie, Crl Schmitt, Zhien Wang, Samuel Haimov and Art Rangno make the claim that "The production of holes and channels in altocumulus clouds by two commercial turboprop aircraft is documented for the first time. ... Holes and channels in supercooled altocumulus clouds can be the result of homogeneous ice nucleation induced by turboprop and jet aircraft at temperatures warmer than previously accepted for commercial aviation influences on…