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Post by Bill W on Feb 19, 2013 9:26:18 GMT
Hi All,
I've had some emails about the Russian fireball and NLC's.
I don't have any detailed figures about the fireball but it probably exploded well below the mesopause. However it clearly deposited substantial quantaties of dust into the stratosphere. It will be very interesing to see it there are any unusual stratospheric or mesospheric effects over the coming days and weeks.
Please keep a careful eye on the sky and submit any observations.
Thanks, Bill.
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Post by Frank on Feb 19, 2013 19:53:18 GMT
I saw faint nlc or nlc like clouds from copenhagen 18:14 to 18:25 local time Made me smile Frank
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Post by Julius on Feb 19, 2013 22:49:23 GMT
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Post by Julius on Feb 20, 2013 6:33:49 GMT
I observed and photographed NLC this morning. A bit unusual they were facing nearly directly south of me. They did not extend further than about 10 degrees above the horizon and they were very faint. I am working on uploading the photographs. They will be ready in about an hour.
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Post by Julius on Feb 20, 2013 9:28:55 GMT
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lucid
New Member
Posts: 4
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Post by lucid on Feb 21, 2013 15:58:35 GMT
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Post by Julius on Feb 21, 2013 16:52:30 GMT
Welcome to the forum and an excellent capture. I hope you will share some more NLC in the summer season. These clouds are indeed mysterious. There seems like they should have a connection to the Russian fireball. I see from the EXIF data attached to the images that they were taken at 0654. What timezone is your camera set to is it GMT/UTC? I observed the same clouds the same morning at 0556 GMT/UTC on the 20.02.13 from Norway.
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lucid
New Member
Posts: 4
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Post by lucid on Feb 21, 2013 20:32:04 GMT
GMT. I was flying the early morning Glasgow to London, Luton.
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Post by Bill W on Feb 21, 2013 20:42:55 GMT
Hi, Nice annimations. I'm glad you titled it "nlc LIKE clouds". I'm always a bit wary about such sightings. I saw the very same thing on Sunday evening! They were faint, low down cirrus combined with atmospheric haze they look just like nlc. What was the solar depresion angle? This is the key as it dictates if the right height in the atmosphere is illuminated. It's tricky! Cheers, Bill.
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Post by Bill W on Feb 21, 2013 20:49:15 GMT
Hi Lucid, Welcome to the forum. It gets pretty lively over the summer months. It'll be good to hear about your observations from your elevated perspective! Bill
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Post by Julius on Feb 21, 2013 21:41:55 GMT
GMT. I was flying the early morning Glasgow to London, Luton. Thanks for the additional info. Hi, Nice annimations. I'm glad you titled it "nlc LIKE clouds". I'm always a bit wary about such sightings. I saw the very same thing on Sunday evening! They were faint, low down cirrus combined with atmospheric haze they look just like nlc. What was the solar depresion angle? This is the key as it dictates if the right height in the atmosphere is illuminated. It's tricky! Cheers, Bill. The solar depression angle was 6° at the start of the sequence at 0658(GMT+1). Sunrise at 0740. I was up looking from 0630 but I did not think to look to the south, so I probably saw the clouds a bit late and then they dissapeared at about 0720 (GMT+1) For Lucid first image, the time is 0654 GMT, Stellarium tells me that the sun was 12° below the horizon at that point at Birmingham ground level.I had my system time set to UTC/GMT + 1 therefore my solar depression angle was wrong for lucid pictures. The correct should be 0654 GMT at 11km above Birmingham 3° 36'
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lucid
New Member
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Post by lucid on Feb 22, 2013 10:27:21 GMT
At 35 000 ft it is very easy to determine if the clouds are NC or hi level Sirius due to observation of other traffic and the height of the tropopause.
On the day of my observation several other higher level aircraft flew past and the NC was considerably higher than them. Also Sirius don't exist above the trop which on this day was beneath our level. The final clue was that the NC's disappeared as the sun rose; Sirius would remain visible.
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Post by Julius on Feb 22, 2013 10:41:05 GMT
In your last picture with the sun partialy visible, we can see some faint couds covering the upper half of the sky are these the same as the NLC in the two previous shots? I agree with you that it can't be cirrius clouds as you were flying at height of about 11km. It might be that these NLC are denser and thus reflects more sunlight. Since they seem to be barley visible even when the sun had started to rise. The cloud I observed dissapeared before sunrise, but they where much further away from me than the NLC you observed.
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Post by Julius on Feb 22, 2013 11:07:26 GMT
I had my system time set to UTC/GMT + 1 therefore my solar depression angle was wrong for lucid pictures. The correct should be 0654 GMT at 11km above Birmingham 3° 36' There are some new pictures from Beverwijk, Netherlands taken on the 21.02.13. He has given the time at 0626 UTC the solar depression angle is 3° 38' spaceweather.com/gallery/indiv_upload.php?upload_id=76855My pictures had a solar depression angle at 6° 07' at 0558 GMT/UTC to 4° 35' at 0610 GMT/UTC
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lucid
New Member
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Post by lucid on Feb 22, 2013 11:13:12 GMT
The pictures where taken within minutes of each other. I was very suprised to continue to see the NC's as the sun peaked above the horizon but they didn't stay for long after that. But yes the clouds are the same in each shot.
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