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Kopernikuksentie 1
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Ursa Astronomical Association

Pearl clouds - 24.1.2022 at 14.41 - 24.1.2022 at 15.05 Karigasniemi Observation number 104191

Visibility IV / V

When I got out I saw the pearls just almost directly above my head, they were big, glowing. Now in hindsight, they should have been photographed too, and not look at them in amazement with their mouths open. Well, on the beach I tried them too. However, the brightest hs were on the edge of the forest, and the ones on my head were more to my imagination than to some of the characters. All pearls were very mobile, their color and shape seemed to change all the time. The air was really warm, not windy, and before leaving we had a little snow a moment ago.

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Additional information
  • Havainto
    • Pearl clouds
  • Cloud coverage in the sky
    • Covered 1/4 of the sky
  • 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: 3 pcs
Mikko Peussa - 25.1.2022 at 20.08 Report this

Komeita helmiäisiä!

Eero Karvinen - 26.1.2022 at 21.02 Report this

Hienot on helmiäiset!

Pekka Parviainen - 29.1.2022 at 12.51 Report this

Näitä kun pääsisi useammin omin silmin näkemään! Hyvä sentään kun on osaavia kuvaajia ympäri Suomea.

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