Hello everyone,
after several talks with Alec, I decided to make some digging into my old odd radius halos displays to search for rare halos and find out some more 28d halo (and 13d halos too).
Here are some examples of what I found so far that might be interesting to submit here to your assessment. I hope you will find those cases interesting.
For some of them, I still have all the raw files of the sequence, for others, I kept few raw images, but for all of them (exposed here at least) I made various time-lapses to keep sequence in B-R rendering, colour rendering, stacked with 4 or 8 images each, like the one I presented earlier in this blog.
I will start with a sharp display of odd radius circular halos I got last year, in April, at the morning.
I'm not usually an early bird so I can miss some nice displays each year. For this one I got the chance to have the display still available to start a capture from my roof window. The center of my house is a stair tower which offer a nice blocking roof for the spot I am from. Therefore, with the shaprness of the display, the 9° ring was particularly well visible on B-R rendering before the sun comes out of the roof (because the diffusion of the light on the lens add noise up to the 9° ring area).
There is a first image, B-R rendered from a sole raw image, to give a view of the sharpness of the event:
Stacking with the above one as first image, with the 25 following images makes those odd radius halos more clear:
Well, in the light of recent search for 28+° ring, this was one of my first tries even if I was expecting, like for the 13° halo, to find it when the rings are not sharp. But if you don't try, you won't find anything.
So there is a processing the the previous stack to enhance sharp halo first then eventually larger borders ones if any.
There is a folder on my drive, so you can take a look at the time-lapses of the day. As usual, better download it rather than viewing it as a Youtube video, to have a better video compression (as is the original one)
Many years ago, I got a nice odd radius display at sunset, during a day of November 2014. The view is not ideal, as I placed my camera on the edge of a window, look south, with a wide angle rectangular lens, hence the distortion. (EoS 1200D + Sigma 8-16mm, set at 8mm).
I was so amazed by the display I sent it to Nicolas Lefaudeux to have his expertise on the matter. And then he told me I caught the 28° halo, again (but I don't recall why this 'again') ;-)
There is the display, B-R rendered, and unsharp masked.
Unfortunatly, I did not keep any raw file of this event.
There is a folder where are all the remainings.
And any old how, here are some I cannot say it is, but looks like there might be something there.... or not:
And while browsing at all of those, I realized I got at least a dozen of 13° halos, with at least one with the Moon. Which could make a post after this one, for the record.
And a last one, not for the 28d spotting, but only because I like it a lot:
Now, a couple hours after starting this post, I think I may go get some rest ;-).
Greetings from France.
Nicolas R.
Thursday 18 May 2023
Monday 1 May 2023
Time Machine: High Cloud Hastings Arc in China, 2012.02.22
The Hastings arc is among the rarest of all halos, even more so in high clouds. On Feb 22, 2012, XU Guodong was blessed with an outstanding display in Mohe, and became possibly the world's very first person to photograph a high cloud Hastings arc.
The display started in the morning and lasted for at least two hours till noon. XU happened to be on a road trip thus unable to document the event continuously from a fixed location. Most of his photos were taken at two stages of the display, when the sun was at around 15° and 22° respectively.
During the first stage, the typical sun-side Parry elements such as the Helic arc and Tape arcs were not particularly strong. However, the Hastings arc was fairly prominent and very easy to distinguish in unprocessed images. Had XU been equipped with the necessary halo knowledge, he would've recognize the arc at the scene with naked eyes.
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| Early stage of the display when the sun was at around 15°. 4-frame mosaic. Slightly enhanced. See if you can spot the Hastings arc. |
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| Background subtracted version of the mosaic. The Hastings arc stands out nicely. |
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| The original image to illustrate how prominent the Hastings was. |
The display remained strong as the sun rose to 22° elevation, when XU made the second stop of his road trip. At this stage the Tape arcs improved a bit while the Helic arc disappeared. The Hastings arc, together with the Wegner arc, somewhat weakened but was still easily discernible in unprocessed images.
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| 2-image mosaic. Slightly enhanced. Sun at around 22°. |
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| Background subtracted version. Though weaker than during the first stage, the Hastings extends further towards the sun. |
While the sky around the sun was jam-packed with great stuff, the opposite side was also very busy. The highlight absolutely goes to the loop-shaped Tricker arc. XU was very impressed by how the loop gradually shrinks in size as the sun rises.
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| Tricker arc (probably some Greenler and Trankle too) during XU's first stop. Sun at 15°. |
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| Tricker arc during XU's second stop. 3-image mosaic. Sun at 22°. Note how the faint Subhelic arc goes above the 120° parhelia and then touches the upper end of the Tricker loop. The blue spot is quite strong too. |
This display bears great significance in China's modern halo history. 10 years have passed and it still is unchallenged, and will likely remain so for a very long time.
Jia Hao
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