Newest observations

Contact information

Ursa Astronomical Association
Kopernikuksentie 1
00130 Helsinki

Ursa Astronomical Association

Pearl clouds - 9.1.2020 at 20.15 Vaasa Observation number 87323

Visibility Unclassified

Timo Alanko, Vaasan Andromeda

When I went on a business trip, I was amazed at the red circle visible under the moon. Just like a red 22 degree ring. It was hastily retrieved by phone. When I got home, I then had a good time with the stand in the backyard. After all, they turned out to be clouds of color. I haven't heard of such before I noticed. A bright full moon makes this happen. Pretty thin was the gauze as the stars were visible through.

More similar observations
Additional information
  • Havainto
    • Pearl clouds
  • 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.

Comments: 5 pcs
Timo Alanko - 10.1.2020 at 05.34 Report this

Ylläpito vaihtoi näköjään  väripilvet helmiäisiksi.

Lauri Kangas - 10.1.2020 at 17.53 Report this

Tässähän on sinänsä optisesti kyse ihan samasta ilmiöstä kuin väripilvissäkin. Ainut ero on että nämä viime päivinä havaitut pilvet ovat kymmenien kilometrien korkeudella stratosfäärissä toisin kuin tavalliset väripilviä aiheuttavat keskipilvet. Ja siksi vieläkin kiintoisampia.


Timo Alanko - 10.1.2020 at 18.09 Report this

Pilvien läpinäkyvyys johdatteli minua enemmänkin ohuiden väripilvien suuntaan. Päivätaivaallahan ei oikein tuota helmiäisten läpi näkemistä pääse toteamaan. Onkohan jossain kuvaa, jossa helmiäispilvi olisi suoraan auringon edessä/päällä?  Onhan se tietysti ihan kiva, jos tuli dokumentoitua helmiäiset kuun valossakin :) 

Marko Myllyniemi - 12.1.2020 at 16.45 Report this

Enpä muista, että kovin usein olisi tullut Kuun valaisemia helmiäisiä vastaan, joten onnittelut hienosta havainnosta!

Pirjo Koski - 31.1.2023 at 15.34 Report this

Onnittelut haviksesta!

Send a comment

Comments are checked and moderated before publication If you want to contact the observer directly about possibilities to use these images, use the Media -form.



characters left

By sending in this comment I confirm, that I've read and understood the the observation system's privacy policy.