James Adamson from Co. Mayo (S. Ireland) caught a lovely NLC display at 00.45 BST. This is the best image and first structured display I have heard of so far this season. The display was bright with obvious bands. I do not have his email address unfortunately. Did anyone else see anything last night? - I was clouded out here.
Here's Jimmy's image. I am sure he won't mind me sharing it here...
Now that's what we're waiting for isn't it? A pity we're rained off here this weekend - we should have some clear nights from Tuesday onwards - indeed Tuesday night looks excellent all round with visibility shown as "Good"
Well James, when I researched the subject prior to my radio interview last year I found that there seems to have been a significant increase in sightings after the explosion of Krakatoa in 1883 although there are some records of sightings as far back as 1845. These seem to rule out the suggestion available on other websites that they're a side-effect of a US military plot to combat "global warming" by increasing the Earth's albedo although there is some evidence to the effect that jet aircraft exhausts are doing exactly this!
My own pet theory is probably controversial :-) I believe that "global warming" is predominantly a solar phenomenon, which is why we can see evidence of it happening on Mars as well as the Earth, and that it is slightly increased solar activity which affects the atmospehere, both in terms of NLCs and the amount of CO2 that is pushed out of the oceans. There are, I believe, pretty strong correlations between NLC sightings and sunspot activity.
Note that this does not mean that "global warming" is nothing to worry about, and there are plenty of good reasons to cut back on fossil fuel dependence anyway, but that the atmosphere may be a lot more complex than some would have us believe.
I don't know of any sightings from ancient times, but, NLC's were observed as a unique phenomenon from late Victorian times, around 1885 (post-Krakatoa), onwards. I know there are possible sightings before then but there are obvious difficulties confirming them. They do appear to follow the solar cycle but the relationship isn't precise; safe to say though that you tend to see more NLC's during the years near solar minima. With luck this trend will be evident this year! It certainly was in 2006...
One area we do still seem to be ignorant of is the frequency of NLC during the southern hemisphere summer. Has anyone here looked into this? The only systematic observing records I've seen from the southern hemisphere are those published in Fogle's book (from memory these were made in the mid-60's) and it appeared that the frequency was comparable to northern hemisphere numbers.