Good day all,
Hypercanes are a highly theoretical type of hurricane that was never observed (fortunately) and can be only assumed / modeled at this time.
They differ highly from tornadoes, just like regular hurricanes do, but both have an eyewall and similar vortex structure (just the size and dynamics are different). Hurricanes (and hypercanes) need a low shear environment to develop, while all tornadoes depend on high shear and a different heating / triggering mechanism.
Basically, a hypercane, if one was to form, will be about the normal size of a regular hurricane. The CORE flow of the hypercane, however, will be much more intense (and tighter) than the eye and eyewall of a regular hurricane. From space, it would look like an intense hurricane, most likely exhibiting a "pinhole" type eye (like Wilma in 2005, or Forrest in the Pacific in 1983).
Basically, what you would have is a "normal" hurricane until one procedes to the inner core of the system. From the edge of the storm, you'll have a tropical storm forced wind envelope (roughly a few hunderd miles wide over 37 MPH) surrounding an area of hurricane forced winds (about 100 miles wide over 73 MPH).
However, within the hurricane-forced wind envelope, there would be a very small eye and eye-wall, about 10 miles wide, with a 2.5 mile wide eye and cloud tops (hot towers) reaching over 100,000 feet (20 miles)! This is where the pressure would fall from about 950 MB to 700 MB in a 5-mile wide "band" with the accompanying winds going from about 100 MPH (outside this eyewall) to 300-500 MPH inside (just before the calm, and very small eye).
Structuarally, this eyewall and eye will be similar in many ways to a large tornado, such as the 2.5 mile wide Hallam storm in 2004, or Greensburg in 2007. It is much higher and wider (10 miles total) and embedded within the outer (and weaker) winds. The eye basically will be a "tube" and clear, proportionally having the dimensions of the cardboard insert of a roll of paper towels vertically.
Most of the thermal energy should be exchanged in this core feature. 120 degree SST's and up would have an incredible amount of energy and result in the low pressures (700 MB, or about 10,000 feet of the lower atmosphere simply "gone" due to the low pressure) and the violent winds.
Expectingly, anything, or anyone unlucky enough to be chasing and / or in the path of such a storm coming ashore would be ripped to shreds and / or scoured away to bare ground. 500 MPH has about 9 times the kinetic energy of a 150-200 MPH wind. This would be like sticking your hand into the slipstream of a commercial jet at speed near sea level. Any small airborne debris, even sand and pebbles, will have the same kinetic energy as a bullet from a .38 or 9mm at such speeds, let alone a car or cinderblock at 500 MPH.
Suprisingly, one such a storm comes ashore, and is cut off from the hot water, the storm will instantly lose its viloent core, then suffer the same dying fate as most (normal) hurricanes do over land.
Also, if the hurricane moves away from the oceanic hot spot of 120+ degree F water, the inner core would also loosen up and weaken. If the cooler water around the hor spot (created by a volcano or impact) is over 80 degrees F, then the hypercane should weaken to a regular hurricane, with a 20-30 mile wide eye and winds 75 to 150 MPH (depending on heat content, shear, etc).
If the storm moves off the hot spot and into cool waters (below 80 degrees), then the hypercane will weaken to a hurricane, then TS, then weaken altogether. Like any normal hurricane, any vertical shear / dry air entrainment also will weaken a hypercane. Convection still needs to remain vertically stacked to support it as it is being heated from the underlying sea surface (Ocean Air Interface). A highly sheared tropical system over a 120+ degree F hot spot may not become a hurricane, but a tropical area of disturbed weather / trough with thunderstorms feeding off the extreme heat content of un-precidented intensity.
Having a situation where the entire ocean (or large portion of it) has been heated to the hypercane threshold (such as 120+ deg F), then larger and longer lasting hypercanes would be common place.
Basically, a hypercane is driven by the SAME thermal forces as a normal hurricane is. It is simply the higher equillibrium (top speed) of the winds related to the extra heat available for energy transfer. This is the same reason why a race car reaches 250 MPH when your family car of similar weight only reaches 120 MPH = Both are cars, just one has a lot more power (horsepower) and higher equilibrium (top speed).
One other thought is the ASSUMED structure of a hypercane. We all (and literature) assume a hypercane will be a tight system and with a very small and high-velocity core. This is being based on that most violent hurricanes and typhoons have a small pin-hole eye (like Wilma in 2005 at 190 MPH). What about an annular hypercane. This should be possible to consider as well. Imagine a 100-mile wide wind field of 350 MPH winds?
A hypercane also will have very strange effects on the atmosphere. The small and violent core will also lift salt water high into the atmosphere (like a regular hurricane does) but due to its high "hot towers" near its core to 20 miles, salt and sea spray will be "injected" into the lower stratosphere. Particularly, sodium chloride and other salts will be photo-degraded by sunlight and UV at these altitudes, yielding chlorine and other ozone-depleting chemicals.
My two-cent's worth...
