APOD: Nacreous Clouds over Lapland (2023 Feb 09)

[APOD Robot]

Nacreous Clouds over Lapland

Explanation: Vivid and lustrous, wafting iridescent waves of color wash across this skyscape from Kilpisjärvi, Finland. Known as nacreous clouds or mother-of-pearl clouds, they are rare. But their unforgettable appearance was captured looking south at 69 degrees north latitude at sunset on January 24. A type of polar stratospheric cloud, they form when unusually cold temperatures in the usually cloudless lower stratosphere form ice crystals. Still sunlit at altitudes of around 15 to 25 kilometers, the clouds can diffract sunlight even after sunset and just before the dawn.

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[Ann]

Nacreous Clouds over Lapland. Image Credit & Copyright: Dennis Lehtonen

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No one has answered yet, so I'd better say something.

This is a beautiful image, and Swedish television has recently shown us similar clouds over northern Sweden. Today's APOD is from Finland, east of Sweden.

The nacreous clouds "are related to" the noctilucent clouds that we see in the summer at latitudes comparable to southern Sweden. The similarity is that both the nacreous and the noctilucent clouds form in the stratosphere at very cold temperatures, and they shine in the sky before down or after sunset (noctilucent clouds can shine all night).

But the noctilucent clouds are blu-ish, whereas nacreous clouds are multicolored. Don't ask me why!

Noctilucent clouds over my hometown of Malmö, July 5, 2020.

Ann

[Chris Peterson]

Nacreous Clouds over Lapland. Image Credit & Copyright: Dennis Lehtonen

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No one has answered yet, so I'd better say something.

This is a beautiful image, and Swedish television has recently shown us similar clouds over northern Sweden. Today's APOD is from Finland, east of Sweden.

The nacreous clouds "are related to" the noctilucent clouds that we see in the summer at latitudes comparable to southern Sweden. The similarity is that both the nacreous and the noctilucent clouds form in the stratosphere at very cold temperatures, and they shine in the sky before down or after sunset (noctilucent clouds can shine all night).

But the noctilucent clouds are blu-ish, whereas nacreous clouds are multicolored. Don't ask me why!

Nacreous clouds produce their visual effect through diffraction, which tends to create colors. Noctilucent clouds shine by reflection and a bit of scattering, which is why they are white or blue.

[Fred the Cat]

Having Finnish grandparents who migrated to Astoria, Oregon, today's APOD gave me chills. It got a little chillier investigating the sights and sounds of Lapland.

Water laping around while you watch the northern lights shows a intestinal fortitude now lost in my own genome. I do retain one tradition.

[nrt]

What is the importance of mountains in the creation of these clouds? I have read multiple times they help in the process, but considering the height of the clouds (15 - 25km) and compared to the usual mountains in these areas are just 1 - 2km tall (if even that) I just don't get how they would matter.

[Ann]

What is the importance of mountains in the creation of these clouds? I have read multiple times they help in the process, but considering the height of the clouds (15 - 25km) and compared to the usual mountains in these areas are just 1 - 2km tall (if even that) I just don't get how they would matter.

I don't think mountains have anything to do with the formation of nacreous or noctilucent clouds. Lenticular clouds are another matter. They do form in the presence of mountains.

Lenticular clouds over a mountain. Photographer: I don't know.

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Opensnow wrote:

A lenticular cloud is a good "forecast indicator" as tall mountains accentuate incoming high-level moisture well ahead of an approaching front. This interception of high-level moisture forms lenticular clouds, and as a result, they are a good warning sign of an approaching weather front and sometimes a big snowstorm.

Ann

[orin stepanek]

I don't much care how they are formed; but they do add to the beauty of the sky surrounding mother Earth!

[johnnydeep]

What is the importance of mountains in the creation of these clouds? I have read multiple times they help in the process, but considering the height of the clouds (15 - 25km) and compared to the usual mountains in these areas are just 1 - 2km tall (if even that) I just don't get how they would matter.

I don't think mountains have anything to do with the formation of nacreous or noctilucent clouds. Lenticular clouds are another matter. They do form in the presence of mountains.

Lenticular clouds over a mountain. Photographer: I don't know.

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Opensnow wrote:

A lenticular cloud is a good "forecast indicator" as tall mountains accentuate incoming high-level moisture well ahead of an approaching front. This interception of high-level moisture forms lenticular clouds, and as a result, they are a good warning sign of an approaching weather front and sometimes a big snowstorm.

Ann

That pic of lenticular clouds is impressive! I wonder if it is normal for them to be stacked ziggurat-fashion like that, in mimicry of the mountain they form above...

[Pixelskiesastro]

Great image!

[SeedsofEarfth]

This seems to me to be more of a meteorological discussion than an astronomical one.

[Chris Peterson]

This seems to me to be more of a meteorological discussion than an astronomical one.

As we discover more and more planets, and start observing details of their atmospheres, the two have significant overlap.