Per thewiki entry about hurricanes/ tropical cyclones I don’t see anything about theoretical maximum size for a hurricane. Are there theoretical limits on how big a hurricane can become?
Evidently the answer is yes, however that limit may be changing.
Found this paper on the subject. I confess I only read the abstract.
The Coriolis effects that give rise to hurricanes also mean that a hurricane can’t cross the equator. So at an absolute upper bound, a hurricane could be 90 degrees in diameter. I’m sure that in practice, though, the limit is much smaller: You could probably approximate it by taking the northernmost and southernmost latitudes which hurricanes have ever reached.
I scanned it, too, and it says to me that there is an upper limit to the strength of hurricanes based on the available energy present in the environment. This seems like a “Duh!” kind of paper, as we’ve seen Gustav and Ike wax and wane based partly on the sea surface temperatures they encounter. But, hey, somebody has to speak the truth. I have also read past hurricane forecast discussions (as an example) that have mentioned that Cat 5 hurricanes can’t sustain that intensity for very long. It may have to do with the centripetal force generated by high speed winds being greater than the angular momentum at the eye wall, causing the eye to dilate after a while. This dilation would result in slower wind speeds. Hurricanes can also go through eyewall replacement cycles that cause fluctuations in wind speed.
I’ve skimmed through the paper itself, and there is a graph that shows a positive logarithmic correlation between sea surface temperature (which is a major source of energy for a storm) and the maximum intensity of the storm. The paper is tying the effects of global warming to a potential increase in the maximum strength of tropical storms, concluding that if the sea surface temperature increases, so will the maximum potential storm strength.
Vlad/Igor, weather phreak.
I’m pretty sure I remember Katrina doing this before it hit landfall. Of course it decayed quite a bit from cat 5 before it hit, but the weathermen were talking about it’s eye wall cycling in strength once it hit cat 5.
Thanks for unleashing your geek and reading the thing.
I’ve been reading up on hurricanes this season also. There are a lot of complicated things going on which all depend upon one another. One interesting thing I read was that thunderstorms within the storm are necessary for its continued existence.
Anyway, I felt as though the answer to the question was yes, there is a size/intensity limit, but I don’t know enough about it to explain why that is.
Weather studies and forecasting involve a lot of thermodynamics and fluid dynamics, and I think the answer lies somewhere in there. I’ve studied some thermodynamics on the microscopic cellular level, but the same rules apply to hurricanes (which is a pretty cool idea that two vastly different things in size and composition obey the same energy laws). I’ve read the hurricane forecast discussions over the past 5 years, and have learned a lot just from the side comments and parenthetical explanations. The NHC forecasters have a sense of humor that shows through from time to time as well.
Vlad/Igor
A separate (also hijack-y) topic is why hurricanes almost never (but, not never) form in the South Atlantic below the Equator, at all.
From wiki:
“A South Atlantic tropical cyclone is an unusual weather event. Strong wind shear (which disrupts cyclone formation) and a lack of weather disturbances favorable for tropical cyclone development make any hurricane-strength cyclones extremely rare”
Yep, I remember that, and I remember the “lack of weather disturbances” part being a little question-beggy.
Hurricanes/tropical storms can only form, and can only grow stronger, where the water surface temperature is above 27.5 C (81.5 F). Their track is a product of the Tropical Easterlies (“trade winds”?) combined with coriolis movement on a planetary scale, which normally takes them out of the nurturing environment. They begin dying as soon as they’re over (a) cooler water or (b) land – though with the sheer amount of energy the cyclonic vortex channels, that can take a long time to dissipate, hence the destruction when they make landfall.
So one theoretic maximum is the amount of contiguous water surface area that is/can be heated to “hurricane nursery temperature.” The tropical part of the North Atlantic, as well as both North and South Pacific, both east and west, contain such warm-water “hurricane nurseries.” Southeast Asian typhoons, Aussie/NZ “cyclones,” and hurricanes off the Pacific coast of Mexico, are fairly common occurrences. The thing is, for Anglo-Americns, the hurricanes that affect us are nearly all from the Cape Verde and Gulf of Mexico warm-water reservoirs. Hurricanes off Mexico’s west coast tend to move out to sea, not hit land – though there are devastating exceptions. This also relates to [bh]Huerta88**'s question about the South Atlantic – it’s a fairly narrow ocean, with cold currents along the shores. So while small warm-water areas no doubt are present in the southern summer, and probably “tropical waves” do occur, they never have a chance to grow to tropical-storm or hurricane force.
The hurricane FAQ at NOAA has a plethora of neat facts that will tell you maybe more than you ever wanted to know. 
http://www.aoml.noaa.gov/hrd/tcfaq/tcfaqHED.html
The largest hurricane/typhoon on record is Typhoon Tip, which had a 675-mile radius in the northwestern Pacific back in 1979. With a distance of 69 miles between lines of latitude, that means Tip spanned nearly 10 degrees latitude(!) at its max extent.
Reasons that you wouldn’t expect a hurricane or typhoon to get much larger than that include a need for sufficiently warm sea surface temperatures (> 80 deg. F), and the presence of wind shear. Cooler SSTs deprive the storm of energy, so if part of the storm extended over an area with SSTs below 80 deg. F, the storm would lose strength and probably start to collapse. (Cold SSTs are also part of the reason that you don’t generally get hurricanes off the coast of California.) Vertical wind shear, as well as wind shear by upper level winds, have the effect of lopping off the top of the hurricane/typhoon and causing the storm winds to become disorganized, leading to collapse of the storm.
Vertical wind shear is a major contributing factor to the lack of hurricanes in the South Atlantic, by the way. The other contributing factor to lack of South Atlantic hurricanes is the absence of the Intertropical Convergence Zone (ITCZ), which normally provides the upward convection and thunderstorm activity that spawn cyclones in the North Atlantic. South Atlantic SSTs are not so much of a factor.
Jupiter has storms larger than most planets. However, Jupiter-sized storms relative to Jupiter are small compared to Earth-sized storms relative to the size of the Earth.
I think a practical limit would be based on energy available, energy required (i.e. depending on the mix of nitrogen, hydrogen, water, methane, ammonia, et al. for your storm fluids), size of the sphere, speed of rotation. An absolute theoretical limit for a given fluid mixture would probably just need sphere size and speed of rotation (available energy assumed to be arbitrarily large).