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Post by mesospheric on May 25, 2010 16:34:33 GMT
Dave Sandford at Bath Uni has kindly set this automatically-updating graph of mesospheric temperatures within an area set at 2 degrees north of Anglesey, together with the values for 2009. The frost point is quite conservative, when one considers how active 2009 was and where the line lies. Keep checking back for updates - the data is delayed by about 2 days. I hope you find it as interesting as I do.
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Post by markt on May 25, 2010 17:08:16 GMT
That's a great graph John! Anyday soon hopefully for the first sightings! Anychance you could resize the image - it's a bit wide, much better when you can take it all in one go. Mark
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Post by mesospheric on May 25, 2010 18:24:42 GMT
Hi Mark, Sadly not; I have no control on the image generated by Bath Uni, so you'll have to either save the image or preferably make a note of the link below and bookmark it for checking back later: people.bath.ac.uk/djs28/NLC/Temperature_Plot1.jpg[thinks a bit more...] What do you make of the marked dip in temperature (presumably real data) in January 2009? There have been a few reports of out-of-season NLC, but always dismissed as not NLC. This graph for 2009 looks like it could happen on rare occasions.
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Post by markt on May 25, 2010 20:05:47 GMT
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Post by mesospheric on May 26, 2010 6:45:10 GMT
Thanks Mark! With all the iPhone, FaceBook, radio and e-mail stuff flying around, I'm beginning to suffer NLC-knackerdness very early on this year, so IT stuff gets a wide berth!
Ta for the link, too. I'll ask the team at Bath what they make of that dip at some point.
Looks like a run of poor weather for me for the next few days. Over to the rest of you for the first sighting!
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Post by clippo on May 30, 2010 7:37:34 GMT
"The frost point is quite conservative, when one considers how active 2009 was and where the line lies".
that graph is tantalising.
I actually went back and looked at the shots I took last year and noticed that I saw a strong display on July 21st.
Looking at the graph, there were two temperature 'dips' in mid-late July but both were quite a bit above the frost point line.
It would be interesting to see a more detailed graph but based on those facts it looks like displays can occur at around -120.
Actually, the other thing that I notice about that graph is that it says it shows the temperature of the mesosphere 'above the UK'. Well, aren't the clouds we are seeing much further North than the UK? I mean, if they are 50 miles high yet only appear low on the horizon...... maybe that accounts for the frost point line anomoly. Maybe the temperature of the mesosphere is colder further North?
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Post by mesospheric on May 30, 2010 9:19:30 GMT
Clippo: the satellite is looking at a square patch of sky a couple of degrees north of my latitude, so that the factors you mention are taken into account; remember that it's set up for my particular experiment for the BBC, although it is obviously of relevance to much of the UK. Many, indeed most displays last year were not low on the horizon but extended to several tens of degrees above it; on about three or four occasions they extended across the whole sky-something that was slow to be accepted as true by some.
The frost line is theoretical, hence it is not an absolute fixed point but merely a guide.
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Post by clippo on May 31, 2010 15:49:41 GMT
that's interesting. I wouldn't have thought it would be possible for a full sky display because of the angles involved. Have you got a diagram (or link) to show how this occurs?
From what I've read, it appears that the lowest latitude at which these clouds form is 60 degrees (which is North of Scotland)... again, how is a full sky display possible without clouds occuring at much lower latitudes?
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Post by mesospheric on May 31, 2010 17:23:51 GMT
Hi Clippo.
Interesting questions, and ones that I wouldn't pretend to be an expert in replying to! The occurrence of NLC has certainly been extending much further south than 60 degrees north. The usual range of latitudes is roughly 50 to 60 north. From memory, I think that they've been confirmed as far south as Turkey, at least. The geometry of illumination obviously isn't the same for near-horizon NLC as the ones extending to the zenith and beyond; there must be direct reflection for that to occur, I guess. I also guess it means that, given the quite bright pre-sunrise light of the sky, that the NLC for this to occur must be quite dense.
Maybe someone else can shine light on the mechanisms, if you pardon the expression?
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Post by prezes on May 31, 2010 22:57:24 GMT
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amez
New Member
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Post by amez on Jun 9, 2010 10:10:00 GMT
... automatically-updating graph of mesospheric temperatures within an area set... Does anybody know where I can find similar data over the other areas, for example over Petrozavodsk 61,78N 34,36E? Thanks. About this in russian forum www.astronomy.ru/forum/index.php/topic,2799.msg1264420.html#msg1264420
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Post by ediacara on Jun 9, 2010 17:34:18 GMT
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amez
New Member
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Post by amez on Jun 9, 2010 19:04:12 GMT
What we can see on first photo? Sarychev's SO2 :-) And 3 or 5 birds... m.b. crows Attachments:
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Post by prezes on Jun 9, 2010 22:22:48 GMT
@ ediacara I thought the glow near a horizon was connected with NLC high level activity. At the moment I agree that was a volcanic gases. I know SO2 increase stratosphere albedo. Howewer, wchich way material form volcano traveled 8 000km to my location in incomplete day (eruption/pictures date: 12-jul-2009)? @ amez Birds we can see on first picture are: en.wikipedia.org/wiki/SwiftThanks for answering.
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Post by ediacara on Jun 10, 2010 8:39:53 GMT
@ ediacara I thought the glow near a horizon was connected with NLC high level activity. At the moment I agree that was a volcanic gases. I know SO2 increase stratosphere albedo. Howewer, wchich way material form volcano traveled 8 000km to my location in incomplete day (eruption/pictures date: 12-jul-2009)? @ amez Birds we can see on first picture are: en.wikipedia.org/wiki/SwiftThanks for answering. Sarychev was continuously erupting in those weeks, sending great amount of SO2 into the stratosphere that was encircling the northern hemisphere. Here's a pic about te SO2 in the beginning of the eruptive events (first week): earthobservatory.nasa.gov/IOTD/view.php?id=38975It reached Hungary on the evening of 04-07-2009, the last day we saw it's effects was on 05-10-2009. We have a lot of swifts in our town in the summer months. :-)
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