A normal hurricane is driven by upward motion of air due to warm water temps over the ocean.
In a strong lake effect snowstorm, the temperature difference between cold lake waters and REALLY cold air above the water provides enough upward air motion to cause thunderstorms.
Questions:
Is it possible for a tropical-like system for draw energy NOT from very warm sea water, but from the difference between sea and air temperatures (similar to the lake effect described above)?
How do we know this is a hurricane, not merely a cyclonic depression with a clearly defined eye?
The basic elements of a cyclone (rain, high winds) can be produced wherever there is moist air in a low pressure system (relative to the surrounding air). So cyclonic systems can happen at cooler temps (a winter Nor’easter, for example). The specific humidity (amount of water vapor in the air) however would be lower and thus would produce less precip.
In the pic, there would be cool alpine air coming in from the north meeting dry,warm desert air from the south producing a relatively small cyclone.
This really has little to do with the “lake effect”.
I don’t have an answer to the OP question, but rather an area that might prove fruitful in exploration to suggest – the Weather Bureau recently (last year IIRC) added to its “named storms” list the category of non-tropical storms, and this seems to fit that description in terms of air/sea conditions, though they’re talking Atlantic weather as opposed to Pacific, Indian, or Mediterranean.
First of all, this cannot be a hurricane if in fact the water is only 61 degrees unless it has migrated from a large body of warmer water with a temp of at least 80 degrees. (To say nothing of the fact that it would not be called a hurricane if it originated anywhere but in the tropical Atlantic)
Since the water temps do not vary this much (20 degrees) across the Mediterranean (excepting for small localized phenomena such as Venetian sewage outlets) this system either migrated from the tropical Atlantic against prevailing wind patterns (virtually impossible)
OR
it is not a hurricane at all, but a Localized Cyclonic Depression.
The difference between hurricane and LCD? The amount of latent heat energy stored in water vapor, temperatures and volume of precipitation. So long as the pressure gradient (difference between the internal low pressure of the ‘eye’ and the surrounding higher pressure) is significant (30 - 40mb between the eye and the outer clouds) one can end up with a system like this - a lot smaller in fact.
Take a torndo for example. The proximity of an Acrtic high and a Tropical low can produce an extreme cyconic system on a very local level.
So in short although the system looks like a hurricane, it is not. If you were on a boat in the middle of it you might not spend much time fondling the nicities that differentiate the two but aside from bringing a stiff breeze and a bit of a gully-washer, its not likely to turn Crete into Atlantis (again ).
When was the last time you saw a extratropical storm with 85 mph winds, a central dense overcast, clear outflow bands, and a perfectly defined, perferctly symetrical eye?
Here’s the hypothetical senario:
A very cold air mass sweeps over a huge body of fairly warm water (say, in the 60’s F). The air temp above the water is very cold, thus, fierce convection occurs above the water’s surface. Thunderstoms pop like mad. The rotation of the earth sets things spining, like it does in a regular tropical system.
You get a storm which looks like a hurricane, smells like a hurricane, quacks like a hurricane.
The last time we had a storm of that description here in eastern Canada was last week. It was about 30 degrees and brought snow. Actually the winds were only about 65mph max, and the eye was only defined before the storm made landfall, but it was basically the same principle.
A continental polar high moved in quickly as a temperate maritime low made landfall. As the storm moved over the Labrador Drift it started to weaken because it no longer had warm air to maintain a strong updraft so it didn’t maintain that typical ‘hurricane look’.
The only thing remotely out of the ordinary in the Med. storm is the clearly defined eye. All that is needed to maintain that eyewall is a strong updraft produced by a pressure gradient of 40mb or so.
