:laugh:
Yup Dave,
although I did say it to you a few times
I was fairly sure you didn't get what I ment.
Anyway Ya,
It's just I was searching on the net for NLC's
and came across this vid on Utube with the tag 'gravity wave'
(the atmospheric / cloud kind
)
eg
I just have seen a few images of these high cloud gravity waves
from space and thought they really do look
like the ripples that are so distinctive in NLC's..