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MAPNUT
2009-Nov-17, 12:27 AM
I saw this cloud on a flight from Istanbul to Rome, about 11am on September 28th. Its hemispherical shape and isolation from any clouds like it struck me as very odd. It was maybe 50 miles northeast of Naples.

My best guess is that it's the early stage of a cumulonimbus, since before it disappeared from view it might have been starting to get an anvil top. And there were thunderstorms every afternoon or evening while I was in Rome. But those were multiple storms, all over the place. Comments?

HenrikOlsen
2009-Nov-17, 01:06 AM
Could be the sign of a city below, with waste heat pushing air up from below.

grant hutchison
2009-Nov-17, 01:30 AM
Yes, it looks like a patch of warmth is driving local convection to pierce an otherwise stable layer of stratus. Sometimes you see this sort of thing over a power station cooling tower.

Grant Hutchison

jrkeller
2009-Nov-17, 01:36 AM
I agree with the others.

mugaliens
2009-Nov-17, 08:19 AM
Or a large lake, warmer than the surrounding air.

I've a few thousand hours flying all over the world (and not in the pax compartment).

I've seen similarly clouds, and countless variations, many times before.

MAPNUT
2009-Nov-17, 01:26 PM
Thanks! I've never seen such a cloud before, but I've only a few hundred hours flying. It's a pity I can't pinpoint the location better. I don't see any suitable lakes on a map - couple of long narrow reservoirs. The cities in that part of Italy are smallish and similar in size - if they could produce a cloud there should be more than one.

adapa
2009-Nov-17, 11:07 PM
Thanks! I've never seen such a cloud before, but I've only a few hundred hours flying. It's a pity I can't pinpoint the location better. I don't see any suitable lakes on a map - couple of long narrow reservoirs. The cities in that part of Italy are smallish and similar in size - if they could produce a cloud there should be more than one.
The other posters are right. In addition, the underlying terrain can also influence the formation of a thunderstorm. A hill or mountain can be place where thermals break away from the ground. An inverted model of this would look similar to how the dew on a cold glass would flow to the lowest point before dripping off. The effect of the hill or mountain is often enhanced if there is a wind that is being deflected upward by it. This is often called an orographic (mountain induced) thunderstorm. This is seen quite frequently when flying over the Caribbean where each island seems to have its own pet thunderstorm (except for Aruba which is flat). Also, the storm does not have to be directly over the source that caused it. The cloud will often be well downwind of its source when the thermals reach the condensation level.:)

MAPNUT
2009-Nov-18, 02:46 PM
Interesting. I've looked at that part of Italy on Google Earth and my best candidate for the cloud-maker is Monte Miletto, about 2000 meters high and rather isolated.

mike alexander
2009-Nov-18, 07:03 PM
Looks like a pastacumulus cloud to me. 50% chance of Alfredo.

Donnie B.
2009-Nov-18, 10:32 PM
Clearly, that's a teenage cloud deck. It's quite common for them to experience cumuloacne at that age.

publiusr
2009-Nov-20, 07:10 PM
I think the term is "overshooting top" http://en.wikipedia.org/wiki/Overshooting_top

HenrikOlsen
2009-Nov-20, 08:04 PM
But that's on an anvil cloud, this looks to be on an otherwise flat cloud cover.

publiusr
2009-Nov-20, 11:09 PM
I think it would still be the same general phenomena

mugaliens
2009-Nov-22, 08:52 AM
Looks like a pastacumulus cloud to me. 50% chance of Alfredo.

Al dente???


But that's on an anvil cloud, this looks to be on an otherwise flat cloud cover.

That is NOT an "anvil cloud."

THIS (http://en.wikipedia.org/wiki/File:Anvil_shaped_cumulus_panorama_edit_crop.jpg)i s an "anvil cloud."

grant hutchison
2009-Nov-22, 01:18 PM
That is NOT an "anvil cloud."Henrik was referring to the term "overshooting top", which does indeed form "on an anvil cloud", as he said.


THIS (http://en.wikipedia.org/wiki/File:Anvil_shaped_cumulus_panorama_edit_crop.jpg)i s an "anvil cloud."It's a lovely picture, indeed, but (for a site intended to be an encyclopaedia) it's a very poor illustration of an anvil cloud.
Here (http://www.wunderground.com/wximage/viewsingleimage.html?mode=singleimage&handle=marsgreen&number=0&album_id=0&thumbstart=0&gallery=) is a picture of a classic cumulonimbus anvil, showing the shape that gives it its name, together with a nice overshoot top catching the sunlight on top of the anvil. And here (http://rst.gsfc.nasa.gov/Sect14/ISS016-E-27426_lrg.jpg) is one seen from above, showing the classic overhanging flat top, again with a bit of overshoot going on in the middle.

Grant Hutchison

flynjack1
2009-Nov-22, 06:31 PM
Hmmm not far from Vesuvius, depending on wind direction and speed. One could expect some up lift perhaps even some venting from that mountain. Either case looks like standard cumulus build ups to me. That time of day would be early stages for development.

mugaliens
2009-Nov-23, 07:25 AM
Henrik was referring to the term "overshooting top", which does indeed form "on an anvil cloud", as he said.

I reviewed the posts, and you're right: My bad. My apologies, Henrik!


Hmmm not far from Vesuvius, depending on wind direction and speed. One could expect some up lift perhaps even some venting from that mountain. Either case looks like standard cumulus build ups to me. That time of day would be early stages for development.

If it is Vesuvius, mountain lifting would certainly explain the hump.

But it looks a bit different than other mountain lifting I've seen. It reads more like a good heat source.

publiusr
2009-Nov-23, 08:26 PM
Doesn't look like any lenticular cloud. Some kind of heating no doubt. Were there any fires in the area (pyrocumulus)?