The Jena diamond dust halos

For at least ten years I’ve been fascinated by the fog-flooded Saale valley. The surrounding shell limestone slopes offer many opportunities to climb over the fog in the morning and discover exciting perspectives. The recent events led me to write this down:

Here’s the chronology of events (jump right into the section):
22.01.2017 | 19.02.2017 | 21.03.2018 | 16.11.2018 | 17.11.2018

Jan. 22nd 2017

On 22.01.2017 we had a high pressure weather situation with ground inversion. The fog wavered between 50 (AGL) and 250m (a.s.l.) slowly dissolving after 8:30 a.m. (CET) to the south (in the direction of Kahla). From my observation point (Mönchsberg) I had a good view on the fog line. Differently than normal something became visible: a light shimmered on the fog – a halo. At about 9:00 a.m. the following picture was taken (sun elevation 8°):

What is this?

If the light is refracted and reflected by ice crystals, a visually (mostly weak) distinctive halo can become recognized. If it is not observed on higher clouds, diamond dust (= ice fog) is usually the reason (exception: on blankets of snow).

So, I drove towards the diamond dust and suddenly saw how everything began to glitter. Now different halos shone around the sun. At about 9:45 a.m. (sun height 10-12°) between Leutra and Maua the following pictures were taken:

22° halo + both 22° parhelions + both sun pillars + both 22° subparhelions
Left 120° parhelion and parhelic circle

In general, the observation around Jena-Maua is very difficult. The new built passage of the B88 with traffic circle and autobahn entrance/exit roads represents a barrier. Quick changes of location are hardly possible.

The next observation succeeded then at about 10:20 a.m. with a sun height of approx. 14°. The light cross in front of the sun became very clear. The whole halo was quite impressive. I had never seen anything like that before.

At the end about 10:35 a.m. (sun elevation 15°) the halo phenomenon showed its full beauty in Maua. Additionally, the Parry arc, Tricker’s src, Subhelic arc and more came to light.

Diamond dust halo phenomenon on January 22nd 2017 in Maua, Jena, Thuringia, Germany

360° panoramic image from the peak display. See the halo details in depth with an unsharp masking before and after:

Total: 18 halo types

22° halo (EE01)
22° parhelions (EE02/03)
Upper 22° tangent arc (EE05)
Lower 22° tangent arc (EE06)
Upper light pillar (EE08)
Lower light pillar (EE09)
Circumzenithal arc (EE11)
Parhelic circle (EE13)
Anthelion (EE17)
120° parhelions (EE18/19)
Supralateral arc (EE21)
Parry arc (EE27)
Subsun (EE44)
Subhelic arc (EE45/46)
Tricker’s anthelic arc (EE57)
Tape’s arc (EE60)
Heliac arc (EE61)
Subheliac arc (EE62)

Here’s a short video documentation:

Claudia Hinz and Andreas Möller have contributed significantly to the determination of the halo types – thanks so much! I also owe the panorama calculation to the latter. More about this and the topic in general in the AKM e.V. forum (German speaking) / Halo-Blog.net (English version) or the Finnish Halo-Blog.

Conclusion

Diamond dust in Central Germany? Wasn’t that a phenomenon of mountains, snow slopes and the Arctic?

Well, the temperature (= dew point) moved between -10 degrees and -6 degrees in the period from 7:45-10:45 a.m. – with a relative humidity of over 95%. That’s quite good!

The formation of the haloactive diamond dust in such a small area (Jena-Göschwitz, Jena-Leutra and Jena-Maua) is supported by the assumption that industrial chimneys release fine particulates as the necessary sublimation nuclei for condensation. By surrounding the area, the origin of glittering ice crystals can be traced back on the basis of wind direction to Jena-Maua.Well – this was just the beginning.

Feb. 19th 2017

Feb. 19th 2017: Subsun + lower light pillar

Diamond dust was visible during the night at my home in Jena-Burgau. So I went to my “backyard” mountain and saw the first halos with a sun height of about 7° and a temperature of -2°C.

8:27 a.m. I took this photo of another beautiful halo display next to Jena-Maua with the rare Moilanen arc (with temperatures tending to 0°C):

The second image showed an interesting area below the circumzenithal arc. While the AKM e.V. sees it as a 46° ring the Finnish researcher Riikonen sees a contact arc there. Who know’s.

Total: 12 halo types

22° halo
22 parhelions (both)
Upper sun pillar
Lower sun pillar
Upper 22° tangent arc
Parry arc(s)
Circumzenithal arc
Parhelic circle
Heliac arc
Subsun
46° ring
Moilanen arc

March 21st 2018

On March 21st 2018 – yep, we had a late winter! – I was documenting another diamond dust display between 9:45 (sun height 29°) and 10:15 (sun height 32°) a.m. in and around Jena-Maua. It is hard to believe but the 2m temperature was between -1°C and +2°C at that time and relative humidity around 70% / dewpoint about -6°C. Surprise – surprise.

Allsky view on an almost complete parhelic circle (unsharp masking)
Welcome to »Maua«!
A beautiful and distinct infralateral arc showed up

While it’s fun to chase the halo for the best sight possible, this is not an ideal place to do so. Maua was recently cut into halfs by a bridge for the new B88 passage. Unluckily the best view of the day was above/under that bridge…
On the other hand I photographed some halos for the first time:

Bright lower 22° tangent arc

Total: 18 halo types

22° halo
22 parhelions (both)
Lower sun pillar
Upper sun pillar
Upper 22° tangent arc
Lower 22° tangent arc
Parry arc
Circumzenithal arc
Parhelic circle
Supralateral arc
Tape’s arc
46° ring
120° parhelions
Heliac arc
Anthelion (see the video!)
Lowitz arcs
Infralateral arc
Wegener’s anthelic arc

For the first time my GoPro recorded the process of chasing the halo lights as a timelapse. Have a look:

If you want to see a contrasted version for further determination, see the unsharp masked timelapse video. Make sure to watch it in 4K-Resolution.

Nov 16th 2018

After flying with the drone over the foggy Saale valley there was a small chance left for diamond dust.

Time: 09:00 (sun angle 10°) – 10:45 (sun angle 18°) AM CET – 2m Temp: -1 / +1°C – Rel. Humidity: 90%dewpoint: -2°C (Sources: TPE / Kachelmannwetter.com).

See the sun rising behind an industry chimney in Jena-Maua with the trail of smoke capped under the inversion. To the left one can recognize that the fog or the industry smoke leads to a diamond dust halo fragment. Again the fog became haloactive…
Since the actual fog shadowed the sun there was no distinct halo display. When it dissolved more and more … the magic started.

Diamond dust halos are a pure 3D experience. This contrasted video in realtime gives you an idea of the glittering ice crystals everywhere:

Halo next to the chimneys of »j-fiber« – a fiberglass production company (in Jena-Maua).

Total: 7 halo types

22° halo
22 parhelions (both)
Lower sun pillar
Upper sun pillar
Upper 22° tangent arc
Supralateral arc
Circumzenithal arc

Nov 17th 2018

By far the best diamond dust halo after the first sighting back in January 2017 was Nov. 17th 2018.

Time: 10:50 (sun angle 18°) – 11:50 (sun angle 20°) AM CET – 2m Temp: -1 /+2°C – Rel. Humidity: 90%dewpoint: -3/-1°C (Sources: TPE / Kachelmannwetter.com).

Encountering such beautiful phenomena of nature makes me feel a deep peace in life.
What a view! 14 halo types at once.
Very good sight on »Tricker’s«
Bright Moilanen arc!

Watch the timelapse documentary below. With 2:10min video begins again as unsharp masked version for a better contrast.

Total: 19 halo types

22° halo
22° parhelions (both)
Lower Sun pillar
Upper Sun pillar
Upper 22° tangent arc
Lower 22° tangent arc
Parry arc
Circumzenithal arc
Parhelic circle
Moilanen arc
Subhelic arc
Supralateral arc
Tape’s arc
120° parhelions
Heliac arc
Anthelion
Tricker’s anthelic arc
Lowitz arcs
Infralateral arc

Résumé

First of all: without the knowledge and help of the German Arbeitskreis Meteore e.V. (short: AKM) these sightings wouldn’t have happened at all. Especially the presentations of Claudia Hinz ignited my fascination for atmospheric optics which is now as strong as my dedication for weather in general.

What do all these sightings have in common?

  1. Locally repeatable sightings around or in Jena-Maua
  2. Relatively temperature independent appearence? 2m maesurement in Jena varied from -10°C to even +2°C with a relative humidity range of 70% to 100%.
  3. The correlation between the ejections of industry chimneys as a precondition and the diamond dust formation seems legit.

Consequences and potential error sources

For the next displays exact on-site measurements are necessary to describe possible contortions. The official Jena 2m temp in the city might be a few degrees higher than close to the fog boundary. Even if I locate a hotspot in Maua the diamond dust has been spotted Saale upriver in central Jena. There might be other yet unrecognized factors or industries contributing to that phenomenon.

If you want to dip into the world of halos you might be interested in the following literature / pages:

  • Claudia & Wolfgang Hinz – Lichtphänomene (German)
  • Tim Herd – Kaleidoscope Sky (English)
  • atoptics.co.uk

Any further documentations will get their own blog entry. For now this is the summary of all personal sightings in the last two years (2017-18) concerning diamond dust. If you’re from Jena and witnessed halos aswell feel free to leave me a message with the dates you saw them.