"Waghorn" wrote in message...

I would suggest this is the expression of a PV streamer and vortex (-ices)
PV streamers have been called 'tropospause shear lines' which suggests
how vortex spin up can occur along them.Unusual appearance in this case
though.Is the central white area caused by convection or convective
overturning (?),

regards,
David

Thanks David. On reflection, any similarity to a Von K vortex is superficial
+ the feature is larger and the cloudless area is quite small.

Karl, Orkney