Noctilucent Clouds

redsteveireland · 23-07-2011 1:59am

Perfect conditions tonight, at last. Can't take any pictures, street light is messing everything up.
:mad:

Iancar29 · 17-08-2011 5:48pm

Think i could of got my first glimpse of Notos Last night,

Was about 3.45 , they looked very high up and very wispy looking , couldnt get a picture though as they wer close to the moon.

Anyone else see them to be able to comment?

Nocto · 25-02-2012 11:55am

Hi, I know this is a bit of an old thread, but you guys seem to know about this. I saw what I think was a noctilucent cloud a few days ago. I'd be certain that's what it was except the shape seems too blobby rather than whispy or net like.

It appeared in the morning, about 6.30 I *think* it was, the sun was to the right and below the horizon. A normal sunrise with pink clouds appeared and covered the noctilucent cloud about 30 mins after these photos were taken. It was very bright, about as bright as the moon, you can see how it was reflecting on the water, and was a cold blue white colour. I couldn't think of any other possible light source, as it was over the ocean(this is a harbour with ocean behind those buildings)

Here are some images, so what do you guys think? Was it a noctilucent cloud or something else?

Su Campu · 25-02-2012 12:51pm

It is not a true noctilucent cloud as they are found over 50 km up, but it does look like a distant altostratus that is illuminated by the morning sunshine where it is.

Where was the photo taken?

DOCARCH · 25-02-2012 2:35pm

Not the right time of year either for noctilucent cloud (to be visible).

Hal1 · 25-02-2012 2:48pm

They can be seen from mid may to august. Those pics do have a similiar resemblance to them though.

Nocto · 25-02-2012 4:23pm

Su campu, how can you tell how high the cloud is? All I could tell was that all other clouds were in front of it and therefore lower...I'm guessing it's the shape? Sorry it's not something I've studied or anything, so this might seem daft. The photos were taken in Skerries, this would be in the....Eastish area of the sky...

And yes Docarch I had read that summer was the "season" for them, but I wasn't sure if this meant they never occurred in winter or simply that they are more likely to be seen in Summer. I thought I saw articles online that indicated they could be seen from ireland in february but I can't find them now. I also remember seeing these "illuminated clouds" being described by another term but I can't remember that and am wondering if there are more than one type of cloud illumination?(other than a common sunrise/sunset that is)

It was very bright and white, really looked nothing like a normal sunrise. Here are some more images of what it looked like as more clouds came in and then when the normal sunrise started and it disappeared.

Sorry if the photography aspect of these images is awful, I'm no photographer.

Deep Easterly · 25-02-2012 5:26pm

Nocto wrote: »

Sorry if the photography aspect of these images is awful, I'm no photographer.

Still ok looking to me

Su Campu & Docarch are right though, it defiinetly is not a noctilucent cloud. Noctilucent clouds are extremely distinctive, very fibrous in structure and almost luminous in hue. I think what you captured is either a higher layered altostratus cloud that was exposed to sunlight further east as has been suggested or a thickening cirrostratus cloud that is lowering into the lower alto(nimbo??)stratus layer that is the dominant cloud feature in the pics.

Do you have an idea of the exact date those photos were taken? and also, was it raining at or around that time?

Edit: Just to add, I have seen similar skies like that here manys the time. I think that the brighter higher cloud if it was observed in isolation would not be all that remarkable but seen again the darker lower based altostratus just helps to enhance it more, making it stand out so to speak. Everything is relative, but always absolute in themselves.

Nocto · 25-02-2012 5:41pm

hehe, maybe I'd better rename these images on all the social networking sites I uploaded them too...

They were taken the other morning, the 23rd of February, from just before 7 til around 7.20. It wasn't raining when they were taken but I do have one photo with the road in it and it looks a little damp, like maybe it had rained during the night. It wasn't a noticeably wet morning though.

It was what I would call luminous, brighter than alot of the noctilucent cloud images I've seen online and as you can see brighter than the pink clouds of the sunrise, and that was when it was nearly faded out.

Deep Easterly · 25-02-2012 6:07pm

Nocto wrote: »

hehe, maybe I'd better rename these images on all the social networking sites I uploaded them too...

They were taken the other morning, the 23rd of February, from just before 7 til around 7.20. It wasn't raining when they were taken but I do have one photo with the road in it and it looks a little damp, like maybe it had rained during the night. It wasn't a noticeably wet morning though.

It was what I would call luminous, brighter than alot of the noctilucent cloud images I've seen online and as you can see brighter than the pink clouds of the sunrise, and that was when it was nearly faded out.

Very likely it is an high based altostratus so that lagged on behind a warm front that moved eastwards over the area the night before.

Infrared sat image at 6z 23rd Feb:

From EUMETSAT.

Su Campu · 25-02-2012 6:09pm

The synop for Dublin Airport at 0700 gave the following clouds:

2 okta stratus at 800 ft, 6 okta stratus at 1,100 ft, 6 okta cirrus spissatus at 22,000 ft.

AAXX 23071 03969 41370 72509 10113 20102 30089 40193 51012 72052 876/2
333 82708 86711 86072=

Cirrus spissatus, by definition, is dense in patches, so I would be confident that that is what the white cloud is. The reason it is white is that it is higher up and therefore receiving the full spectrum of wavelengths of sunlight, whereas lower cloud has a reddish/pink colour due to scattering out of the shorter wavelenths during the sunlight's longer path through the atmosphere.

Deep Easterly · 25-02-2012 6:38pm

Su Campu wrote: »

Cirrus spissatus, by definition, is dense in patches, so I would be confident that that is what the white cloud is.

Most likely explanation alright.

http://namesofclouds.com/cirrus/cirrus-spissatus.html

Popoutman · 26-02-2012 1:13am

To me it looks as though that brighter patch is a gap in the layers of cloud aloowing the pre-dawn clear air above to be seen through the gap. The cloud layers, not yet sun-illuminated, are very dark, and the clear dawn sky is very bright by comparison. I don't think it's a bright cloud occluded by darker clouds, I think it's bright sky occluded by lower dark clouds.

(unless I'm missing something in the photos..)

Nocto · 26-02-2012 12:18pm

Oh well! I guess it's not a noctilucent after all, glad I got an explanation. I guess that's where my confusion came from, my laymans understanding of noctilucent was essentially a cloud high in the sky, illuminated(white/blue in colour) by the sun below horizon, while it was still dark. All of which this appeared to be(to me anyway)

I'm still not sure I understand the distinction to be honest, other than it being the wrong type of cloud at the wrong altitude/time of year, but other than that it all seems the same. I understand what people are saying about the dark clouds making it look lighter too... which is possible obviously, and obviously cameras make it hard to measure light/dark. I guess I'll just have to keep an eye out for a real nlc so I can see the difference for myself!

Thanks for all the help and useful info!

Deep Easterly · 27-02-2012 6:22pm

Nocto wrote: »

I'm still not sure I understand the distinction to be honest, other than it being the wrong type of cloud at the wrong altitude/time of year

That it all it is really. Noctilucent clouds are really only seen around the mid-summer period which is when the mesosphere is actually at its coldest.

A cloud height guide (quality not great as photographed from a book)

Noctilucent clouds are not included due to their rarity and limit of the height spectrum on the graph.

Popoutman · 01-03-2012 11:42am

I still say that the bright patch in the photo is not a cloud at all, but only a gap in the cirrustratus. The dark edges look right, and the timing of the pic and the colour is right for the forward-scattered sunlight off high altitude dust, during the dawn.