A circular cloud in photo

[Christophe]

Photo taken 28 November 2007, 15:04:48 near Paliseul (Belgium): a rather rare atmospheric phenomenon creating a "circular" cloud, but see instead:




Does anyone know more about the conditions necessary for the formation of a circular cloud?

[loop]

hi Christophe

Seeing the 2 photos, my arms almost fell out
You will believe me if you want, I observed exactly the same phenomenon one evening a few weeks ago without ever having seen it before and yet I often look at the clouds
I have no explanation for the phenomenon at the moment but I will investigate
What I can say is that it is not a circular cloud, nor lenticular like those that we observe in the event of a wave, especially in the mountains
Rather, it is a very localized subsidence on an altocumulus bank. Altocumulus clouds reveal significant humidity at a given level, which condenses if there is elevation and therefore cooling. In the photo, it looks like the condensation has turned into ice, as for altitude cirrus clouds, and that there is a very localized descent of air which removes the cloudiness

Awaiting further explanations

A+

[Christophe]

Fortunately, who did not fall, otherwise you would have had a hard time answering ... good joke aside, pkoi is this not a circular cloud (in formation)? I know about queudale there in weather.

Indeed the cloud layer was very high that day.

I have some other photos (but redundant) if you want? If I had known that it was so rare I would have followed its evolution ... but after 1 hour there was nothing ...

What do you think of these 2 there:

[loop]

Christophe

I don't know what you call a circular cloud, what I see is on the contrary, a hole on a cloudy bench
The formation of the central cloud is linked to the very localized physical transformation of the cloud bank
We nevertheless have the impression of a downward suction, as if we were witnessing a sink that empties
An animation would have been more meaningful, can you confirm the evolution of the phenomenon
What formed first and what disappeared?

A+

[Christophe]

Yes for the circular cloud ... it's the opposite ..

Yes we have the impression that it "falls" in the middle ... but it was very slow, no "visible animation".

No idea of ​​the evolution, these are the photos when I noticed the phenomenon ... and I did not follow the evolution as I said

But it quickly disappeared ...

[loop]

For other photos
The one where we see the American flag
It is likely that it is a plane drag in a school of altocumulus

For the other photo, it's more spectacular
It reminds me of two drops of oil on the surface of the water
This is probably a phenomenon which spreads in the cloud layer in a uniform way, which would explain the circular geometry
From which site do these documents come from and what comments are attached to them?

[Christophe]

For the other photo, it's more spectacular
It reminds me of two drops of oil on the surface of the water
This is probably a phenomenon which spreads in the cloud layer in a uniform way, which would explain the circular geometry
From which site do these documents come from and what comments are attached to them?

I thought exactly the same for "oil" ...

I found them here: http://www.spica.org/plugins/diaporama/ ... iapo_id=24

No really "comments" as you can see ...

[Christophe]

Here is a photo taken at about 180 ° at the same time, there is also a rather "clear" curve on the same "amat" of cloud.

[Capt_Maloche]

it looks like a column of localized cold air

[Rabbit]

Same phenomenon photographed by my wife a few days ago.
On Nov 28, 07 at 12:04:52 p.m. above Gembloux (Belgium)
The ring was already busy dissipating, apparently the phenomenon
is very ephemeral. The ring already goes to 9 in a few seconds.