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Ursa Astronomical Association
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taivaanvahti(at)ursa.fi

Ursa Astronomical Association

Other special clouds - 16.6.2021 at 20.29 Tampere Observation number 98970

Visibility II / V


There had been an interesting-looking cloud development in the sky throughout the afternoon, but it wasn’t until the large-scale, multi-layered almond mhaemems (altocumulus lenticularis) finally forced the ‘kids to sing’ (timelapse - i.e., interval shots on) on the balcony.

Just over 70 squares (every 15 s) later, while watching the cloud play, I noticed a strange-looking, upside-down u-vortex (- or cloud) that I recognized as an oitis horseshoe vortex based on an observation I saw earlier in Skyward this year (I'm sure of that). So that's just a classic puzzle for the owner of one working camera: whether to interrupt a great timelapse, or let it sing. Usually when I personally intrigue or otherwise interfere with my series of intervals, either in terms of position or exposure, I always produce a worse imprint. Unexpectedly.

Well. Now, however, it was a rare cloud phenomenon, and I knew that the 10 mm focal length of a cropp cell, combined with relatively long intervals, would probably not even provide confirmation for my visual observation. So I hurried the telezoom to the nose of the camera and after listening to that wonderful ‘antique camera’ back and forth focus saw, this short-lived flow phenomenon was well on its way in the evening - practically over. I got one image at a focal length of 200mm by hand, but it is even more unusable (in terms of a passing phenomenon) than the thumbnail and image-video pile I presented here in connection with the observation.

So, in principle, I interrupted the series singing in vain, but on the other hand, the still cloudy medium, which became more and more interesting, required correcting both the position and the settings. The only intact battery was eventually burned out at 5 s intervals, leaving more than 1,300 RAW squares. Now it was a very nice, colorful and multidimensional cloud play for my own eyes, although the much-needed diamond cirrostrat was not available at all on this tour!

The icy disintegration material of the altocumulus also briefly showed the basic halves: the side sun and the pillar. Plus a perimeter and probably a cloud of color. Maybe a lenticular stack.

I will update this observation in the near future as long as the machine calculates the appropriate end products on the subject.

It will probably be useless, and my own videos turn out to be basic compilations, but I would tentatively urge you to look through the series of photos from today in the Tampere area - for example, from TaUrsa's weather cameras - if you are interested.


Additional information
  • Havainto
    • Other special clouds
  • Cloud coverage in the sky
    • Very small area
  • Other special clouds
    • Horseshoe cloud info

      A horseshoe vortex cloud occurs when an upward flow in the atmosphere collides with a horizontally moving air mass. This may cause a horizontally rotating vortex. If moisture condenses in the vortex into cloud droplets, a very rare upside-down U-shaped cloud shape can be observed. Often such a vortex is only visible for a very short time, perhaps a few tens of seconds or minutes.

      Typically, horseshoe clouds are said to be visible in the vicinity of supercellular storms, as they are associated with very strong upflows and wind torsions that are conducive to the formation of a vortex. Yet this cloud shape is observed just in conjunction with conventional Cumulus clouds and sometimes even very far from them against a completely blue sky. To detect this cloud, you should therefore be careful whenever cumulus cloud is generated as a result of upflows.

Technical information

EOS 500D, Sigma 10-20mm (F / 4-5.6 EX DC HSM) @ 10mm, f11, 1 / 800s, video Snapshots are taken every 15 s.

Comments: 4 pcs
Heidi Hautasuo - 18.6.2021 at 14.07 Report this

Mielenkiintoinen havainto!

Tero Sipinen - 18.6.2021 at 23.24 Report this

Hienot pilvilapset ja hyvät havainnollistukset. Komeat taivaat. Ja onnittelut tarkkasilmäisestä hevosenkenkäpyörteen bongauksesta!

Timo Alanko - 19.6.2021 at 15.25 Report this

Viime päivinä on Vaasankin taivaalla näkynyt mielenkiintoisia, lähinnä undulatus-muotoja. Illalla leijaili pilvissä vaakasuuntaisia putkilon näköisiä aaltoja, ikään kuin vesipatsaita vaakasuorassa. Niille ei liene mitään kategoriaa täällä. Mukavaa, että näin kesälläkin on taivaalla jotain bongailtavaa :) Tuo hevosenkenkäpyörteen huomaaminen osoittaa kyllä melkoista tarkkaavaisuutta!

Tapio Lahtinen - 12.5.2022 at 21.40 Report this

Kalle kun linkitti toisesta havainnosta tämän niin kiinnostaisi tietää että tarkistettiinko TaUrsan sääkameroita.

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