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Ursa Astronomical Association
Kopernikuksentie 1
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Ursa Astronomical Association

Pearl clouds - 16.1.2022 at 09.35 - 16.1.2022 at 09.57 Juva Observation number 103916

Visibility II / V

Petri Martikainen, Ursa (Itä-Suomi)

Behind the pearls lower than the pearls, the jury is nutty. Are the temperatures even possible? Images in reverse chronological order. Figures 1-5 are lightly cluttered to improve cloud separation.

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Additional information
  • Havainto
    • Pearl clouds
  • Cloud coverage in the sky
    • Covered 1/8 of the sky
  • Nacreous clouds
    • Nacreous clouds, type I (acid) info

      Nacreous clouds (mother-of-pearl clouds) are clouds that occur in winter and are best seen at dusk in the morning and evening when the Sun is below the horizon.

      Although the name of pearl clouds refers to spectral colors, colorless, pale nacreous clouds are mainly observed in Finland. A striking feature related to pearl clouds in Finland is also the strong brown, which makes the landscape bathe in intense red or purple light.

      The Sky Watch has categories for colorless elections (type I) and colored (type II) pearl clouds, as well as the brown subtype.

      This selection reports type I colorless pearl clouds. While ordinary clouds are located in the lowest layer of the atmosphere in the troposphere, pearls form in the stratosphere above this at a height of 15 to 25 km above the ground. They occur when the stratosphere is exceptionally cold, about -75 ...- 85 C. The particles that cause pearls are either pure water ice (type II) or chemically different crystals, all of which contain nitric acid (type I) as an ingredient.

      Changes in stratospheric thermal conditions are quite sluggish, which is why pearl clouds are seen continuously for at least a few days unless the lower clouds obscure the view. Nacreous clouds can be extensive in their occurrence and can occur simultaneously throughout Finland. However, the focus of the performances is in Lapland. The appearance of nacreous clouds in the sky can be predicted by stratospheric temperature predictions.

      Nacreous clouds observations made in Finland from 1996 to 2014 show that they had been seen from December to March. Most occurred in December-January, in March nacreous clouds were reported in only one year. The particles responsible for the pearl clouds can also give rise to the Bishop ring. The Bishop’s ring may be a clear sign of nacreous clouds when the Sun is on the horizon. The pearl clouds themselves usually stand out when the Sun is on the horizon, but in this case they are usually very ghostly cloud fibers and easily go unnoticed

      Type I nacreous clouds. Image by Panu Lahtinen.

      Noctilucent clouds like nacreous clouds of type I. Image by Mikko Peussa.

      Half an hour before sunset, wavy nacreous clouds. These nacreous clouds stood out exceptionally well from the daytime sky. Image by Marko Riikonen.

Comments: 3 pcs
Timo Alanko - 17.1.2022 at 05.48 Report this

Itäisen Suomen päällä on ainakin nullschoolin mukaan ollut alle 70 astetta. Tällä hetkellä 71. Ei taida siis pakkanen riittää. Tänään pitäisi olla kirkasta. Katellaan...

Teemu Öhman - 17.1.2022 at 13.46 Report this

Katselin samaa meininkiä Etelä-Pohjanmaalla siinä päivällä ja auringonlaskun tienoilla. Hyvin epämääräistä, mutta epämääräisyydestä huolimatta varsin uskottavan oloisesti siellä yläpilvikorkeuden yläpuolellakin ylimääräistä hussakkaa oli. Ylittivätkö ne sitten sen veteen piirretyn viivan, jonka toisella puolella ne ovat MoPpeja ja toisella eivät, onkin visaisempi kysymys. 

Teemu Öhman - 17.1.2022 at 17.49 Report this

Korjataanpa tuota kommenttiani: Eipähän se oma pilvien ihmettelyni ollut 16. vaan jo 15.1.

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