On the night of April 2 at 11:30 pm, 20 miles east of Pittsburgh, PA there was an very light cloud cover in the east to the west and overhead and no winds. As I went outside, I noticed an eerie black stripe across the sky, stretching from the east to west horizons and forming an arc nearly directly overhead. I turned the flood light out to view it better. I've been a star/sky gazer for 40 years and have never seen this kind of 'parting' of the clouds. The light and continuous cloud covering seemed to have been seperated in a perfect line across the entire sky from east to west. This 'stripe' of black, which was the black night sky with all its stars, was perfectly even across the entire sky, and measured only about 3-4 fingers wide when your arm is extended fully. The clouds appeared whitish in the night, and it appeared as though the clouds had been parted in that narrow stripe formation somehow to expose the black night sky. I called my son (also a star gazer) to look at it and he couldn't imagine how or what could have made such a perfect part in the clouds all the way across the sky. I stood outside observing it for 15 minutes and there being no obvious wind or even a breeze, it stayed nearly the same the entire time. The following day I called the local observatory to ask if possibly a jet flying overhead could have caused a continuous split in the cloud cover like that. He said jets could not have affected the clouds like that, and that if it were a meteor, it would have been observed and reported by someone. I was hoping that someone might help me understand and explain what would have caused this strange parting of clouds.

Wind?

I am not a meteorologist, but the parting of the clouds may have been caused by the passing of a cold front or warm front.

http://atmoz.org/blog/2007/06/10/the-warm-...ront-explained/

http://picasaweb.google.com/david.atl.beno...141938018574514


But if that is true, it must have been raining for some time, and the temperature must have changed.

Hi and welcome to UM....I'm not an avid star gazer, so I can't help you out on what you saw, but it sounds very beautiful...Too bad you didn't get a chance to take any pictures...would have loved to see it....

I would have LOVED to have gotten a picture but I didn't know how I could do it. Now I wish I would have at least tried! I have not had luck at night pictures. But I thought that there would be an easy explanation for it, but so far I have not heard anyone say they have even seen anything like this before. How does a perfectly straight and even part from horizon to horizon occur in the clouds?? I can't imagine that wind up high could just push away such a narrow strip of clouds all that distance!? There was no rain or anything happening that whole day as far as I can remember. The clouds that were up there were so thin that you could see some of the brighter stars through them. In the far south horizon, there were some clouds that formed narrow strips fanning away from where this 'black stripe' began. In the northern and southern sky, there were no clouds at all. In this black stripe area I remember seeing two brights stars nearly overhead that I think was of Leo. I have emailed many of the local TV station weather centers but so far there have been no replies. I called the weekend radio program of Birds and Nature and he never heard of such a thing. He will have a Science Center guest on soon and I will call again. I'm hoping that someone will understand this soon!? In the meantime, I feel fortunate to have experienced it, whatever it was!

lenticular clouds?

I saw something very similar to what you saw on April 18, 2008 at around 10:30 PM, in New York City (Manhattan). A black stripe in the east/northeast sky extending upward. I couldn't see how far up overhead it went, but it is possible it might have arced to the western horizon. I asked two other people if they saw it and they also observed the same thing. A local TV station is near the location where I observed the event .....in retrospect, I should have dragged out a reporter and camera crew to record it.

We get that a lot where I live ... we call it a "convergence zone" ...

Convergence zone usually refers to a region in the atmosphere where two prevailing flows meet and interact, usually resulting in distinctive weather conditions.

An example of a convergence zone is the Intertropical Convergence Zone, a low pressure area which girdles the Earth at the Equator. Another example is the South Pacific convergence zone that extends from the western Pacific Ocean toward French Polynesia.

A smaller example of a convergence zone occurs in the Puget Sound region, known as the Puget Sound Convergence Zone. This happens when winds in the upper atmosphere are split by the Olympic Mountains. The winds then converge beyond the mountains, producing convection uplift that results in the development of clouds and even stormy weather.

Convergence zones can also be associated with sea breeze fronts.

Source

We'll see a distinct line in the clouds where the convergence zone meets. The zone itself can raise north or drop south occasionally. The clouds will often form a perfect line, oddly right at our northern county line.

A good example of how drastic a convergence zone can be... this weekend Seattle got snow... or rather, everyone above the convergence zone did. I had very little snow at my house, but 5 miles north of here, they had 10".

What you saw could have been a convergence zone of sorts?

I have ruled wind out because I can't imagine it moving just a narrow strip of clouds all the way across the sky. This strip of parted clouds is only as wide as 4 or so of your fingers when held at arms length. That is really narrow.

You probably did see the same thing! I can think of a million things NOW that I wish I would have done. I now think I should have called the TV station and had the weather man look out the window! I emailed all of the stations asking the weather people to look into it but no replies. Tonight I noticed how they use weather radar - why couldn't they look in their files and see what the clouds were doing at that time that night for me??? Not important enough I guess. I even tried to call the airport and see if the air traffic controllers noticed it. I couldn't even get to speak to one of them.

I wondered about cold and warm fronts meeting but it had been uneventful weather changes for a few days - in the 40's. That night there was no wind at 10pm and at 11 pm the report says 3mph wind so that's isn't much. It was a very calm night and was reported as 'partly cloudy'.
Someone mentioned 'lenticular clouds' but when I looked those up - they are beautiful and round - not like that night. I've never been so interested in clouds till now. I've taken beautiful pictures of unusual daylight clouds and the photos on the internet are beautiful.

I'm wondering about the 'convergence zones' mentioned also. But these clouds were fairly thin because in some of the places you could see some brighter stars faintly through them. And they were sooooo still. I talked with my son outside looking at them for over 15 minutes and nothing seemed to move at all. We hadn't had rain all day and didn't have any after this. The sky in the north and south was clear. I wish I would have realized it would be such a puzzle and I would have checked on it and seen how long it lasted. Oh well.

[color="#0000FF"][/color][size="5"][/size]Today I contacted the National Weather Center in Pittsburgh, PA and spoke to the Warning Coordination Meterologist, Rich Kane. I told him of the black stripe in the sky and my experience, and his first words were "Yes, that is a DISTRAIL". He actually knew exactly what I was talking about and had done papers on them in college. He said that when the exact conditions are right, the clouds are at just the right level of the jet, the proper amount of moisture in the clouds, and the proper cloud deck, a distrail will happen. A distrail is when the exhaust that comes out of the engines seeds the ice crystals in the clouds and the clouds then fall out and evaporate in a path behind the jet. The jet doesn't actually 'part' the couds - it dissipates them. So my first guess was right, although the man at the Science Center said I was wrong. He suggested that I write another email to all of the weather forecasters that I contacted and tell them so they can learn! By the way, he also said that when you see strange holes in clouds, that is the same thing happening. I can sleep now!!! Thanks for all of your opinions!