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 Post subject: Halo 40,000 ft.
PostPosted: Fri Oct 06, 2017 2:32 pm 
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Joined: Mon Jan 18, 2010 9:25 am
Posts: 5334
13.50 UT. Today.
Very nice day, sunshine with large parallel bands of high cloud, plus sheet high cloud and a few low cumulus.
After cloudless transparent night.

Very strong left very prismatic sundog.
Also faint upper concave stripe. Possibly upper tangential arc on top of 22 degree circle.
Otherwise nothing else seen.
Very much easier to see both when wearing polarised sunglasses.

The cloud was at 40,000ft, presumably radar measure? The halos no height I suppose.

12.50UT 360 deg 8 knots visibility 40km clouds broken 25,000 ft few 40,000 ft 15C TDP 05C 1026 hPa.
This is the first time I have heard of such high cloud here. Usually 25,000ft or 22,000ft. Occasionally 30,000ft maybe 32,000ft? but never before 40,000ft.

Prism sundog nice 1/1500 sec f/7.1 80 ISO.

Regards
David

P.S.
LIDAR for height, maybe sound waves for wind speed. Visibility, a person or an optical ranging instrument.


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 Post subject: Re: Halo 40,000 ft.
PostPosted: Sat Oct 07, 2017 2:51 pm 
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Joined: Sun May 11, 2008 6:11 pm
Posts: 3303
Location: Portslade, Sussex Lat 50deg 51min Long 0deg 13mins West
6th October 2017, 1526. etc: First noticed a nicely coloured right-hand sundog, so went into the street to photograph it, hiding the Sun behind the gable-end of the opposite house. This sundod was very colourful, and at times showing a blue-to-white tail. The photographs captured the colours well, and the prints made in the Boots Machine show the red, orange and yellow very good in enlargedment. Just as I was coming in. I noticed the left-hand sundog appearing, this was similar, the blue of the tail standing out well, especially in the print. These sundogs look like colourful comets with short but obvious tails!! I looked for any other optical effects, but saw none. Two hours later, as the Sun was going down, there was another left-hand sundog, but this one more "vertical" and less colourful. regards maf


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 Post subject: Re: Halo 40,000 ft.
PostPosted: Mon Oct 09, 2017 9:34 am 
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Joined: Mon Jan 09, 2006 11:05 am
Posts: 5361
Location: Lancashire
Parhelions ( aka sundogs ) in Utah: http://www.livescience.com/26402-sundogs.html .

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brian


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 Post subject: Re: Halo 40,000 ft.
PostPosted: Mon Oct 09, 2017 1:41 pm 
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Joined: Mon Jan 18, 2010 9:25 am
Posts: 5334
16 degree circle also?

Regards,
David


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 Post subject: Re: Halo 40,000 ft.
PostPosted: Wed Nov 01, 2017 9:32 pm 
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Joined: Mon Jan 18, 2010 9:25 am
Posts: 5334
2017 Nov 1 ~15.17UT.
Cloud 24,000ft maybe. ~15C.
Most sky covered but didn't seem to be a continuous sheet.

Right sided prismatic sundog, centre about 9 or 10 degree elevation.
About 2.5 degree up and down making about a 5 degree part of 22 degree radius halo.
Sun expanded weak. (Yesterday, about the same time, the Sun was an enormous weak expanded area).
Possibly unseen left sundog hidden by buildings?
Seen better visually than on the photos. Forgot to try polarised sunglasses.
1/1250 second f/4.8 80 ISO.

Regards,
David


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