What causes this perfect hole in the night sky cloud?

a reply to: CX

I guess my question would be then whether or not it was actual cloud cover or was it just a really really thick foggy haze of ice crystals causing a circular light refraction effect ?

You guys get some pretty dense fog across the pond...

So if it was clouds and not a thick haze of ice crystals, then maybe you witnessed what's known as a hole punch cloud ?

Link


And yes, if it stretched for miles around, it would be a freaky sight !

This is what is known as a 22 degree halo. It is caused by ice crystals suspended in the atmosphere. Light from the moon comes down. Refracts into these ice crystals in one direction and comes out at another. (22 degrees) thus causing thw halo shape.

This is a common occurrences but can't usually be seen that well. I myself saw it last Night too and was amazed.

When you see these you can be sure cold weather will follow. The vast majority of people who saw this are most likely experiencing snow fall at the moment.

a reply to: CranialSponge

Thanks. I did look at hope punch clouds last night, i just couldn't find any pictures as perfectly circular as big as this one.

There's always an exception though, after all, mother nature never fails to surprize us.

CX.

a reply to: capragenus

I'm so glad someone else on here saw this last night, it really was cool to see.

You're right, we now have our first snow in ages.

Thanks for the explanation.

CX.

originally posted by: CranialSponge
a reply to: defcon5

I believe the OP is talking about a dark circle that extends beyond the moondog halo around the moon...

That's part of a moon ring/dog. The whole effect's called a moon ring. If you get image moons at the 3 and 9 o'clock positions, it's a moon dog.

The dark area's created by concentrating the light that would have gone there into the bright ring. It's all one piece. Also, if you look really carefully, you'll see that the inner edge of the bright ring is reddish - if the moon's light were a bit more balanced spectrally you'd see a rainbow where the ring is.

op: the thing's caused by a high layer of very thin clouds composed of ice crystals. They're not so thick you can't see through them, unless they're lit up by the moon light. Then they glow with dispersed moon light and look opaque. Within the center area of the ring, it's dark, because the light's been diffracted over to the ring structure. With no illumination (or not much) in the middle, you don't SEE the thin layer of cloud and can see stars through it, because it's not back-lit. So it can look as if there are no clouds there. If the moon weren't up, you'd see a slight haze obscuring the dimmer stars.

a reply to: CX
Hey CX and fellow Brit I'm in South essex finished work at 10 last night and when for a stroll and smoke through the wood. Got to a clear spot and looked up an noticed exactly the same as you. It was quite an awesome sight

I'm not here to call you an idiot or anything but I was led to presume that what causes this is indeed ice crystals. I believe what you may of seen as in clouds was actually a mist that with the moon light may of made it look like clouds. Either way great pics I tried taking one myself but my phone wasn't up the to the task

Nice catch !

a reply to: ThePeaceMaker

Yeah i guess the ice crystals just gave the impression of cloud cover. Was pretty cool to see.

Cheers.

CX.

I think what you are seeing, is actually earths shadow being cast by the sun directly behind where you are standing. If you werer to look at where you are standing in 3-d, then th sun would be on the other side of earth, as you are looking up, seeing earths shadow, being cast directly above. Its either that, or the moon itself is causing the shadow to be cast. but i believe this to be the sun doing this

a reply to: CX
Don't take me reply the wrong way I could be totally wrong about how the ice crystals could look like cloud cover. Was just sharing my thoughts

I took this last night in the south west of the UK

I've seen the same thing out where i live. I'm glad you posted this. A layer of clouds over the whole sky like a sheet but almost in a perfect circle around the moon there is no clouds. A strange phenomena for sure. a reply to: CX