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Watsisname
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24 May 2020 07:03

midtskogen, I saw and photographed an amazing ice halo display here yesterday! We had the usual 22 degree halo, along with the upper/lower tangent arcs, and the parhelic circle (faintly). I suspect I may have also caught some of the less common halos like the 46 degree halo, or perhaps just the supralateral/infralateral arcs -- I'm not completely sure. There was also a small but striking circular halo within the 22° one, but I have no clue what it would be.  Any ideas?

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midtskogen
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24 May 2020 11:59

Nice.  I think you identify correctly.  I haven't seen a complex display here at this time of year, but in winter when the ice crystals are at "ground level", the halos and arc can become very bright, even the rarer ones.

As for the smaller, inner ring, I am not sure.  My immediate thought was that it was formed by pollen, a "pollen corona".
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24 May 2020 16:04

Nice, thanks! I was first thinking of a pollen corona as well, since I didn't really know what else it could be. However, it lacks the more vivid colors and brightening around the Sun that is typical of corona. But when I searched around for info on smaller ice halos, I couldn't find anything, so I was left scratching my head.

Now I happened to look at Atmospheric Optics Picture of the Day, and boom, there I think is the answer. It appears to be the 9° halo, caused by pyramidal ice crystals. I did some image measurements, from which I get a ratio of inner to 22° halo radii of about 0.394, or an inner halo radius of about 8.7°. With some error, it seems like a good match.

Atopics gives some insight as well as to how uncommon these displays are.  During 10 years of observations in Europe, for every 100 times a 22° halo was seen, the 46° halo and parhelic circle were seen about 4 times, and pyramidal crystal displays were seen only 0.3 times. Wow.
 
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24 May 2020 23:57

Send your pictures to Les Cowley, I'm sure he'll find the inner circle interesting.  I was also thinking that the inner circle was a bit colourless.  I've never seen a circle like that.

How uncommon really depends on your location.  I would say that the 46° is pretty common in Scandinavia during winter, regularly appearing together with the 22° halo.  This is when the halos are observed within the crystal cloud.  It takes humid air and temperatures below -10 °C, and that is not rare. Even the "rare" Moilanen arc I see nearly every year where I live, though I only look for it when there's a nice display.  The theory is that it's formed by snow machines, of which there are many within a few km and they run whenever they can in December (and ice halos are most frequent during Dec to Feb when temperatures are at the lowest).  But since I see it so often, I still wonder if it can occur naturally.

The best display here that I've seen was this:
Image
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26 May 2020 00:30

midtskogen wrote:
Source of the post The best display here that I've seen was this:

That's spectacular. I dream of seeing arcs near the anthelion, those seem so surreal...

Here ice halos are somewhat common in spring and summer when we have high altitude crystal hazes, but usually it's just the 22° halo and parhelia. I once many years ago saw a very bright and complete parhelic circle which lasted about 15 minutes, and alas I had no camera. But it introduced me to the amazing variety of ice halo displays that are out there. This last display though was easily the best I've seen so far, and I was glad not just to photograph it but also enjoy with several friends and neighbors (at a socially safe distance). :)

I forwarded some photos to Les, hopefully we'll get some feedback.
 
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26 May 2020 04:42

The season for noctilucent clouds has begun in Oslo.  Last night:
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04 Jun 2020 11:40

A large landslide caught on camera in Norway yesterday.  All occupants of the houses escaped in time (minutes to save).
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22 Jun 2020 01:03

My first sighting of noctilucents here this year, and third sighting in all. The display was nearing its end by the time I noticed them, but might go out again later this morning to see if they're still around.

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22 Jun 2020 05:13

 Nice capture, Wat!  Are these clouds the result of meteoric dust, and what kind of camera settings do you need to capture them?  Were they as visible in person as they appear to be in the image?
 
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22 Jun 2020 07:41

A-L-E-X wrote:
Source of the post Nice capture, Wat!  Are these clouds the result of meteoric dust

Thanks!  I'll have more to share in a moment, as well.

Are they the result of meteor dust? The dust may act as a condensation site just like it does in the lower atmosphere, but the clouds themselves are made up of small crystals of water ice. Interestingly though, there aren't much historical records of observations of these clouds before 1885, after the Krakatau eruption. They're curious and stunning enough in person that it would be pretty weird to have not been reliably described before then. And they seem to be growing more common in modern times. 

The thinking among atmospheric scientists is that this is due to more water vapor being available at those altitudes. We also see them more often after large rocket launches, especially the Space Shuttle launches. Other factors might include the cooling of the upper atmosphere due to the enhanced greenhouse effect (the less-often mentioned flipside of global warming -- the upper atmosphere cools down!), and the increasing concentration of methane. In the upper atmosphere methane can form water through reactions with hydroxyl.

A-L-E-X wrote:
Source of the post and what kind of camera settings do you need to capture them?  Were they as visible in person as they appear to be in the image?

They are very visible and a silvery to eerie electric blue to the eye. My photo above is a few seconds exposure and it appears somewhat brighter and more colorful than what the eye sees. It is similar to capturing aurora.

Critical to seeing noctilucent clouds is high latitude. They appear most often above about 50° latitude and in summer. They can be seen from lower latitudes too, but less often. Too high of latitude can also be bad since the summer nights don't get dark enough.

Timing-wise, the best time to view is in astronomical twilight and closer to nautical twilight, when the Sun is between about 12 and 15 degrees below the horizon.  When the sun is below -15 degrees they are seen only very low to the horizon, while when the Sun is above -12 degrees you begin losing them to the brightening sky.
 
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22 Jun 2020 09:10

More that I managed to catch this morning, but by then it was just very thin wisps. An animation to show their weird movement (about 8 minutes in real time).


Image

I would have captured more to get a longer animation, but in the middle of it I was distracted by something unexpected: a spectacular train of sky pollut -- I mean Starlink satellites.

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22 Jun 2020 09:57

Wow was this a 4K timelapse?  I dont have a 4K recording device but the resolution in this video seems to be higher than what I see in regular videos.

The two types of clouds I haven't seen and have always wanted to see are noctilucent clouds and nacreous ("mother of pearl") clouds.....have you seen this type also?

Also, since we were talking about unusual weather earlier.....I found this historic occurrence mentioned on Twitter, the first recorded 100+ temp north of the Arctic Circle, figures it would be Verhoyansk in Siberia, either that town or Omyjakon or Yakutsk records the highest temp extremes.....from -90 in winter to (now) +100 in summer!  Did you see these forest fires occurring so close to Arctic Sea Ice?

I've noticed hotter temps occurring farther north this year, seems like the attic fire that started in the high Arctic has spread farther south and has now reached northern VT and Maine with temps approaching 100 there, all time records.

https://twitter.com/weatherdak/status/1 ... 3052469249


that has videos of the fires in northern Siberia

here is the official record of the 100.4 temp at Verhoyansk

https://twitter.com/capitalweather/stat ... 9216476160

Ugh those starlink satellites, couldn't they have constructed them of a metal with a low albedo so the light pollution wouldn't ruin the view of the sky for us?

That's interesting about these clouds higher frequency might be GHG related....and methane is almost 100x as potent as CO2 as far as GHG are concerned, also cooling down the stratosphere is connected to warming in the lower part of the atmosphere isn't it?  On weather forums I always read about a SSW (Sudden Stratospheric Warming) event being linked to colder winters....so one would think a colder Stratosphere would mean a milder winter?

We've already seen the negative effects of a snowless winter here......nasty explosion of bugs this year, with a horde of gnats near my Poconos home that makes working in my garden impossible.  I thought it was just this community but when I went down the mountain to a nearby town, they were mobbing people there too!  I've also had to spray bug barrier throughout my other home on Long Island, where I now have wolf spiders along with their eggs (eek), I saw one in my bedroom and could not sleep there for a week!  They are hairy, with warning stripes on their legs, black and grey (to warn others of being poisonous) and I haven't had these in a decade or so.  I sprayed so much bug barrier to get rid of them that my throat and nose were burning!  I just hope I dont get any centipedes later on, because I haven't had them in a long time either.....it's the combo of a warm wet winter followed by a warm wet spring and now this hot humid weather that has caused this population explosion of bugs.  I wish all the birds I get in both gardens would eat them all up, but they seem to be content singing and taking baths in my pond!  We also have a 50% reduction in monarch butterflies (an important pollinator) because of pesticides killing their favorite food, milkweed, as well as the changing climate.  But now everyone is planting milkweed along the roads and highways, so maybe they will have a comeback?
 
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22 Jun 2020 22:43

A-L-E-X wrote:
Source of the post Wow was this a 4K timelapse?

Nah, just some frames from the DSLR. Which is 4K resolution (4272x2848), but I cropped the images down quite a bit.
I haven't seen nacreous clouds yet. I'm not sure if they're as common at my location, but I keep an eye out for them, too. :)
 
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23 Jun 2020 11:42

Watsisname wrote:
Source of the post  Interestingly though, there aren't much historical records of observations of these clouds before 1885, after the Krakatau eruption.

I don't think this is very conclusive.  There are hardly any clear descriptions of the aurora borealis either going back more than a few centuries.  Greek and Roman writers describe the long winter nights of the north, surely if they saw the aurora, they would have described it?  Well, no records exist which clearly describe the aurora.  Yet we can be pretty sure that the aurora was there.

Watsisname wrote:
Source of the post when the Sun is above -12 degrees you begin losing them to the brightening sky.

I think it depends on your latitude.  At your latitude, the clouds are likely only seen low over the northern horizon, so it needs to be fairly dark.  At higher latitudes, however, these clouds can cover the entire sky, and then you need the sun closer to the horizon to touch the clouds towards the south.  The northern horizon might then be too bright, but who cares if the rest of the sky is filled with these clouds?

Nacreous clouds are interesting.  They can be insanely bright, so if you try to photograph them, either the clouds will be overexposed or the landscape underexposed.
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23 Jun 2020 12:56

midtskogen wrote:
Watsisname wrote:
Source of the post  Interestingly though, there aren't much historical records of observations of these clouds before 1885, after the Krakatau eruption.

I don't think this is very conclusive.  There are hardly any clear descriptions of the aurora borealis either going back more than a few centuries.  Greek and Roman writers describe the long winter nights of the north, surely if they saw the aurora, they would have described it?  Well, no records exist which clearly describe the aurora.  Yet we can be pretty sure that the aurora was there.

Watsisname wrote:
Source of the post when the Sun is above -12 degrees you begin losing them to the brightening sky.

I think it depends on your latitude.  At your latitude, the clouds are likely only seen low over the northern horizon, so it needs to be fairly dark.  At higher latitudes, however, these clouds can cover the entire sky, and then you need the sun closer to the horizon to touch the clouds towards the south.  The northern horizon might then be too bright, but who cares if the rest of the sky is filled with these clouds?

Nacreous clouds are interesting.  They can be insanely bright, so if you try to photograph them, either the clouds will be overexposed or the landscape underexposed.

I didn't know about the rare clouds connection to climate change before.....will have to look into it further.  Tell you what though, what's been going on in Siberia for several months now is pretty conclusive.  I understand why Russia is in the business of denialism too, they think Siberia is going to be the world's new bread basket.

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