A while ago Jack Harrison published a gliding photo of an unusual hole in a
high cloud deck over mountains.
An idea I've had is that it was the top of a fall streak hole caused by wave
interaction.I've now found a precedent for the idea-
Annales Geophysicae (2002) 20: 711 - 715

An explanation for some fallstreak clouds
R. M. Worthington

Abstract. Fallstreak cirrus clouds are associated with super-saturated
air, together with waves, instabilities and/or turbulence; however, their
precise cause is usually uncertain. This paper uses already-published
satellite, radiosonde and radar data, reanalysed to study some large
fallstreaks which had been previously overlooked. The fallstreaks - up to 60
km long with a parent cloud 20 km wide - are caused by lifting and/or
turbulence from a mountain wave, rather than, for example, Kelvin-Helmholtz
instabilities. If turbulent breaking of mountain waves affects ice particle
formation, this may be relevant for the seeder-feeder effect on orographic
rain, and the efficiency of mountain-wave polar stratospheric clouds for
ozone depletion.

online at-


http://www.copernicus.org/EGU/annales/20/5/711.htm

(Sorry Jack-lost yr address and my guess was bounced back to me)

--
regards,
David

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