I do understand that hurricanes are “fueled” by warm water - that is, the energy that drives the wind, rain, and pressure differentials comes ultimately from heat flowing from ocean water to the cold, upper atmosphere. But how does this process get amped-up in a centralized, relatively small area?
There must be some positive feedback mechanisms at play; the winds and/or rains fueled by heat flow must themselves facilitate and amplify the heat flow. What are the processes involved? And why do they concentrate over an “eye” instead of dispersing over the ocean?
To offer a few answers, there’s a lot of factors that go into a hurricane.
One is a low pressure system. There are typically zones of low or high pressure in the atmosphere, mainly due to uneven surface heating. We see these all the times in weather reports (the Ls or Hs of high or low pressure systems). They happen over water, too. And in a low pressure zone over very warm water, storm formation can happen very quickly.
Unless the sun heats the entire surface of the Earth evenly, they’re going to always happen.
The rotation in the system comes naturally from the rotation of the Earth. The energy from large open swaths of warm water. There are naturally storm systems along fronts over the ocean, just like on land. But during the summer, there’s more heat to work with so those storms can get really, really big.
So, low pressure system, warm water, and the earth’s natural rotation are all factors.
As for that energy dispersing over the ocean - well it does to some extent. Hurricanes lose their punch after passing over colder water or experiencing wind shear or passing over land. That happens to weaker storms as well, before they can form into a tropical system. We (well, the non-meteorologists) just don’t notice those most of the time.
Things that can inhibit formation include dust. Saharan dust blowing over the Atlantic often keeps some of those systems from really forming and we saw some of that earlier this year. Wind shear is another factor that can disrupt formation (and why there aren’t so many South Atlantic systems). Wind shear often picks up this time of year in the western Gulf of Mexico, which is why it’s comparatively rare for strong October hurricanes to hit Texas rather than Florida.
Note, this isn’t unique to Earth. We see cyclones on Jupiter and Saturn as well. When there are temperature and pressure differences plus rotation, they’re going to happen anywhere there is an atmosphere to let them occur.
The eye is a low pressure area. Air comes from a high pressure area into the low pressure area. But by the time it gets there, it’s moving so fast that it goes right past, then gets pulled back and orbits the low pressure area. The storm is all constantly getting sucked into the eye, but not actually getting there.
The air in the eye is low pressure because (fluid dynamics), but also because it is being sucked out by the anti-cyclone operating above the hurricane, which is spinning the air out.
Isn’t the Giant Red Spot a big hurricane?
Although it makes our biggest storms look puny.
The wiki on
is pretty good at explaining this at an approachable level of detail.
There’s actually a region of low pressure air down low driving the infalling rotation which then exhausts vertically into the upper atmosphere where a contra-rotating high pressure outflow develops to keep everything in balance.
Thank you. I thought that perhaps water evaporation and condensation was a factor in maintaining the cohesion and strength of hurricanes. But, if I understand correctly, the low-pressure eye persists because the Coriolis effect prevents surrounding, higher-pressure air from entering.
Jupiter’s Great Red Spot is an anticyclone, which is a central region of high pressure which drives circulation rotating the opposite direction that the lower winds would be driven by Coriolis forces. It is thought to be the same system first seen about two centuries ago. Nobody knows what drives it but a leading theory is that a plume of hot ammonium hydrosulfide is being injected into the upper atmosphere by some process below that drives and sustains it. Since we can’t directly visualize or measure the interior atmosphere of Jupiter, there are numerous speculations on what those processes could be but without being able to send a probe deep into Jupiter’s atmosphere (which is way beyond planetary exploration technology now and for the foreseeable future) or come up with a clever way to measure the interior dynamics with neutrinos we just can’t really test any hypotheses.
Saturn and Neptune also have large anticyclonic storms discovered by the Voyager probe (just Voyager 2 for Neptune, of course): Anne’s Spot for Saturn (still visible during the Cassini flyby in 2004) and the Great Dark Spot on Neptune, which was not found by the Hubble Space Telescope on 1994. How persistent these systems are is unknown, as are the processes by which they are initiated and sustained but given the distance of both planets to the Sun it is virtually certain that they are strictly driven by internal dynamics of the atmosphere.
Stranger
The Coriolis effect isn’t really that strong. It persists because it takes a lot to transfer that much air.
“Higher-pressure air” sounds a bit off. There are pockets of air that are higher pressure and others that are lower. Yes, there’s movement from one to the other, but it’s not like it’s some kind of instantaneous transfer of pressure.
Look at low pressure systems over land - those don’t dissipate either, and they’re a lot weaker and smaller.
I think you’ve chosen the wrong word. Coriolis effect has an indirect effect on the formation of hurricanes: it causes the counter-rotating east-west winds, which are part of the trigger, and which determine the original direction of rotation. But the cohesion of the storm is caused by fluid dynamics and thermodynamics.
They have an astounding union and they are outside the purview of the NLRB.
I came in to post witticisms, but I have been beaten to it, dammit.
I assumed this was true; I’d like to know what the fluid dynamic and thermodynamic effects are and how they contribute to maintaining a hurricane as a single storm. Again, I assume there is feedback involved: rain - water evaporating at the surface and condensing in the upper atmosphere - would transport heat, and somehow the energy released must be driving conditions that favor further evaporation. Maybe the winds contribute; maybe more warm water is being drawn into the eye region. Is the process still a mystery? Or is it, perhaps, reproducible by computer modeling but too complex to be described in human language?
What metaphysical nonsense. It’s bog standard boring physics. The air and water and energy can’t do anything other than exactly what it does. Which we can simulate in detail with our fidelity limited only by our ability to gather accurate starting point data on a fine-enough mesh. The concepts behind a tropical storm are trivially easy. If you understand basic 100- & 200-level college physics.
Read and understand the articles I posted in response #5. If you don’t understand those, read and understand all the inline references to other more foundational articles. You’ll get it. I’m confident in you.
When you’re done, come back with well thought through questions. We’ll be here.
What I (and probably a few more people) aren’t going to do is summarize a 10-page wiki article for you when you need all that detai to have it make any sense. You just gotta read it yourself.
The operation of cyclones is just normal weather: sun heats the surface, surface heats the air, warm, light air is underneath high, cold, heavy air, which is unstable, which causes weather.
Air is warmed by warm ocean, rises, and is replaced by cold air rushing in. The longer it lasts, and the warmer the ocean, the faster and harder it spins.
The tricky bit is just why hurricanes start, or don’t start. Why aren’t there hurricanes all the time, or never hurricanes? Why do storm cells turn into twisters? Unless I missed the message, the difference between “all hurricanes” and “never hurricanes” is still too close to call. Certainly it’s not possible to predict “a hurricane” except in lab conditions. All they can do is predict “hurricane season”.
But you could still post something about Democrats 
Just an interesting tangent about the direction of these storms depending on which hemisphere they start in:
Probably big money from the weather channels too.
yep, big weather money …