"Darren Prescott" wrote in message
o.uk...
Now visible at 1955Z between WSW and NW, these are
considerably higher than the other 'normal' Ci fibratus clouds
I can see nearby at about 30000ft.
Volcanic, apparently:

http://www.spaceweather.com/

Thanks, Darren for bringing this website to my attention, now
added to my favourites.

Clouds of volcanic origin... something that should have dawned
on me as a possible explanation because I do recall observing
skies of this ilk on the odd occasion in the past. The streamers
and waves I saw yesterday, closely match those shown in the
last photograph (taken by Rob Bullen in the Forest of Dean) of
the 2009 Sarychev Sunset Gallery on the 'spaceweather' site.

Thank you also, Stephen, Martin, Philip and 'BatMan' Nick,
for your observations.

Took a squint outside just now (2000Z) and they've reappeared.
Although less distinct than at this time yesterday evening, ripples
are now visible within the striations.

Nigel