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Skywarden,
Ursa Astronomical Association
Kopernikuksentie 1
00130 Helsinki
taivaanvahti(at)ursa.fi

Ursa Astronomical Association

Pearl clouds - 17.1.2022 at 14.30 - 17.1.2022 at 15.30 Sodankylä Observation number 103995

Visibility III / V


Beautiful pearl clouds on Kiilopää. Visible rather low.



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Additional information
  • Havainto
    • Pearl clouds
  • Cloud coverage in the sky
    • Very small area
  • Nacreous clouds
    • Pearl clouds of type II (ice) info

      Pearl clouds (Nacreous 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, colored (type II) pearls are rare in Finland. We mainly see colorless, pale (type I) pearls. 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 type I and II nacreous clouds, as well as the brown subtype. This selection reports pearl clouds representing type II spectral colors.

      While ordinary clouds are located in the lowest layer of the atmosphere in the troposphere, nacreous clouds 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 pearl clouds 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. Pearl cloud 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 pearl 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.

      In the winter of 2012-2013, Finland experienced an exceptionally long 13-day pearl cloud streak. On the second to last day of the episode, rare spectral colors also appeared in the clouds. Photo by Matti Helin.

Technical information

Canon 5D4, 200mm

Comments: 8 pcs
Mikko Peussa - 18.1.2022 at 21.44 Report this

Hienot kuvat helmiäispilvistä! Mukana näyttää olevan myös tyypin I helmiäispilviä (happo). Selvemmin kakkoskuvassa.

Tero Sipinen - 18.1.2022 at 22.34 Report this

On kyllä hienoja!

Saataisiinko vielä timelapse helmiäisistä, kiitos! (pitihän tätä kokeilla, kun edellinen taivaanvahtiin laitettu tilaus onnistui niin hyvin :) 

Satu Juvonen - 19.1.2022 at 12.27 Report this

Kiitos!  Sorry Tero :)  Kävi kyllä mielessä timelapse, niin kiehtovasti muutti muotoaan tuo spiraalipilvi. 

Pirjo Koski - 22.1.2022 at 23.07 Report this

Ihan uskomattoman komeat kuvat! 

Satu Juvonen - 23.1.2022 at 22.52 Report this

Löytyykö nuo sfäärien lämpötilat jostain? 
Kiitos Pike! 

Lasse Nurminen - 24.1.2022 at 11.18 Report this

Esimerkiksi täältä löytyy sääpallojen luotausdataa. Kartassa näkyy maailmanlaajuisesti noita asemia, Suomesta löytyy kaksi kappaletta (Jokioisilta ja Sodankylästä). Sitten vaan zoomailee kartalta sopivan aseman ja klikkaa siitä.

Aukenevan sivun yläosasta näkee vielä otsikkoriviltä päivämäärän, jona viimeisin aseman luotaus on suoritettu. Toinen pystyrivi vasemmalta näyttää luotauskorkeuden ja kolmas rivi lämpötilan kyseisellä korkeudella. Neljäs sarake näyttää kastepisteen, joten tarkkana kannattaa olla. Jonkun kerran kiireessä yltiöpositiivisena katsellut väärältä riviltä, että kylläpä onkin kylmää :D

Satu Juvonen - 24.1.2022 at 12.00 Report this

Kiitos Lasse linkistä ja ohjeista! 

Timo Alanko - 25.1.2022 at 13.44 Report this

Tuo on myös aika selkeä seurantapaikka. Siellä Air, temperature ja 10 tai 70 hPa. https://earth.nullschool.net/#current/wind/isobaric/10hPa/overlay=temp/orthographic=-334.25,72.48,2107/loc=20.831,63.445

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