Emily looking much better on SAT PICS.

[T-man]

This is all very interesting, and would be even more so if Mike would kindly provide some credentials............

[jax]

you are right on target Mike...

[Wthrman13]

Sorry to jump in on this, but I feel I should back up Air Force Met on this.

A bunch of buoyant air being shoved by more buoyant air from underneath and thereby creating high-pressure aloft should not be automatically assumed to be converging. -- A helium ballon doesn't sink until it's popped, and latent heat-of-condensation warmed air parcels don't sink either until they expanded and cooled (which is why the stuff over Emily is just sitting there, queued up to flow outward and away).

You are forgetting mass continuity. The rising air coming out of the top of the eyewall convection has to diverge. It does so both inward toward the center of the eye, and outward. This means that aloft over the center of the eye you have converging air. There is no escaping it. This converging air, then, by mass continuity, must also sink.

Nonsense; it can stay right where it is, remaining buoyant. For instance, we could all stand on chairs and repeatedly punch a helium balloon bouncing along the ceiling -- and it's not going to go down. The high-pressures at the top of a hurricane are the result of upward buoyant pressure to expand; and unexpanded (and thereby cooled) parcels of such buoyant air aren't going to sink under the influence of not-more-greatly-bouyant air surrounding it. Consequently, there must be some other phenomena explaining downdrafting in eyes, and I have submitted internal eddying to account for it.

And, as I opinioned back a few posts, if hurricane eyes were analogy to ordinary high-pressure ridges (which are closed loop systems involving convection in lows at their peripheries involving exhaust from the lows being fully expanded, cooled, and descending in the centers of the highs), then the lowest pressure readings in a hurricane would be in a ring under the eyewall, not in the center of the eye (which would, instead, exhibit high pressure).

Ok, I think I see where the hangup is in this discussion. The air coming out of the exhaust of the hurricane has lost virtually all of its buoyancy, and even if it is still buoyant by the time it reaches the tropopause, mixing with stratospheric air will quickly remove any residual buoyancy by bringing the exhaust air in equilibrium with the surrounding air. This is where your balloon analogy breaks down, because the air inside the helium balloon retains all of it's buoyancy, since it is not allowed to mix with surrounding air, and also because it would have to rise to a much much higher level in the atmosphere than a simple ceiling before it's density is comparable to the surrounding atmosphere. So, lets say for the sake of argument that the air exiting the convective updrafts in the eyewall is neutrally buoyant, a fair assumption. The only forces acting on the air at that point are dynamic ones, that is ones driven by vertical and horizontal pressure gradient forces. Thus, at the top of the eyewall, there are horizontal pressure gradient forces acting both inward and outward from the perturbation high, which has a ring configuration. Again, we agree, the high pressure aloft is created by the rising buoyant air below. Therefore, some of the (nearly) neutrally buoyant air is forced inward toward the center of the eye, while the rest expands outward. The air that approaches the center of the eye from all sides is thus converging. Since it is at best neutrally buoyant, this will create a situation where the air is forced downwards, since if it tried to rise, it would become negatively buoyant rather quickly upon encountering the very warm and stable air of the stratosphere. Thus, it sinks. Simple mass continuity.

Now, that said, if the air retains sufficient positive buoyancy, I can envision where some of it might be trapped for a while directly over the top of the eye, being held in by the inward directed PGF from the top of the eyewall, but being unable to sink because of positive buoyancy. Thus, a balance might be struck between the downward PGF aloft due to the converging air, and the upward directed PGF, and the air would not move. However, it is unlikely the air would maintain its positive buoyancy for a sufficient time to allow this, and also, as the hurricane becomes stronger, the downward directed PGF at the top of the hurricane would also become stronger, potentially overwhelming the positive buoyancy of the air. Again, refer to my analogy of the kid with the beach ball in the pool. We are not talking about punching a helium balloon and allowing it to rise again, but rather applying a continuous force to the balloon (i.e. me grabbing the balloon and forcefully making it descend toward the surface). This is, in effect, what happens in a hurricane's eye. Subsidence due to the downward PGF overwhelms the positive buoyancy of the air, and the air sinks. This sort of circulation is thermally indirect. I think you err here in implicitly assuming that the circulation must be thermally direct (warm air rises, cool air sinks). In the case of the hurricane's eye, the warm air sinks under the action of a continues downward PGF. Warm continental high pressure regions, like those that dominate over desert regions, are also thermally indirect in this sense, in that the warm air is sinking, converting the kinetic energy of the flow into potential energy (stored as the thermal energy of the air through compressional warming). Thermally direct circulations, in contrast, like that of the hurricane eyewall, convert potential energy of the warm buoyant air into kinetic energy of the flow (through accelerating the updraft and also via mass continuity, increasing the low-level convergence). Cold, continental high pressure ridges are thermally direct in that the cold air is sinking in the center, which is what you are referring to.

Again, to recap, the circulation in the eye of the hurricane itself is thermally indirect, forcing warm air to descend through mechanical pressure gradient forces and converting kinetic energy to potential energy (manifested as the warm low-pressure anomaly), whereas the circulation in the surrounding eyewall is thermally direct, where warm buoyant air is rising, converting potential energy to kinetic energy. I think the trip-up here is that you are failing to acknowledge thermally indirect circulations. Hurricanes have both types.

[mahicks]

http://www.aoml.noaa.gov/hrd/tcfaq/A11.html

I'm not going to get into your discussion which, by the way, is absolutely fascinating...But I would like to give you Kudos for the cool link....It's amazing what is on the NOAA website

[mike18xx]

All I can say is...it should be pretty easy for the average reader to make up their mind...since your sources are "Me" and all the pro-mets are citing the best in the business.

My "sources" are the observable evidence (in the form of previously cited and re-cited Isabel loops), AFM. The purpose of science is to continually explore and explain and test theory. A theory ossified via literature is not rendered unassailable, and anyone resolutely quoting "experts" whose explanations do not adequately account for the observed evidence in question is not practicing science -- he is engaging in theology.

[mike18xx]

This is all very interesting, and would be even more so if Mike would kindly provide some credentials............

"Appeal to Authority" logical-fallacy duly noted.

http://www.totse.com/en/ego/literary_genius/devils.html:

REGALIA, n. Distinguishing insignia, jewels and costume of such ancient and honorable orders as Knights of Adam; Visionaries of Detectable Bosh; the Ancient Order of Modern Troglodytes; the League of Holy Humbug; the Golden Phalanx of Phalangers; the Genteel Society of Expurgated Hoodlums; the Mystic Alliances of Georgeous Regalians; Knights and Ladies of the Yellow Dog; the Oriental Order of Sons of the West; the Blatherhood of Insufferable Stuff; Warriors of the Long Bow; Guardians of the Great Horn Spoon; the Band of Brutes; the Impenitent Order of Wife-Beaters; the Sublime Legion of Flamboyant Conspicuants; Worshipers at the Electroplated Shrine; Shining Inaccessibles; Fee-Faw-Fummers of the inimitable Grip; Jannissaries of the Broad-Blown Peacock; Plumed Increscencies of the Magic Temple; the Grand Cabal of Able-Bodied Sedentarians; Associated Deities of the Butter Trade; the Garden of Galoots; the Affectionate Fraternity of Men Similarly Warted; the Flashing Astonishers; Ladies of Horror; Cooperative Association for Breaking into the Spotlight; Dukes of Eden; Disciples Militant of the Hidden Faith; Knights-Champions of the Domestic Dog; the Holy Gregarians; the Resolute Optimists; the Ancient Sodality of Inhospitable Hogs; Associated Sovereigns of Mendacity; Dukes-Guardian of the Mystic Cess-Pool; the Society for Prevention of Prevalence; Kings of Drink; Polite Federation of Gents-Consequential; the Mysterious Order of the Undecipherable Scroll; Uniformed Rank of Lousy Cats; Monarchs of Worth and Hunger; Sons of the South Star; Prelates of the Tub-and-Sword.

-- Ambrose Bierce, The Devil's Dictionary, 1881-1906.

[Air Force Met]

All I can say is...it should be pretty easy for the average reader to make up their mind...since your sources are "Me" and all the pro-mets are citing the best in the business.

My "sources" are the observable evidence (in the form of previously cited and re-cited Isabel loops), AFM. The purpose of science is to continually explore and explain and test theory. A theory ossified via literature is not rendered unassailable, and anyone resolutely quoting "experts" whose explanations do not adequately account for the observed evidence in question is not practicing science -- he is engaging in theology.

Sure...whatever you say.

[mike18xx]

How scientists would resolve a dispute like this: Equip a Gulfstream with dye-rockets (of the sort aerial barnstormers use in displays) to be fired at various high altitude layers in the stable closed eye of a mature hurricane, then note their changing altitude (if any) on subsequent passes. (Possibly the dye would also be observable on 250m VIS zooms.) If air at all altitudes in the eye is sinking, then the established literature is correct. If air at high altitudes is not sinking (but much lower layers in the eye are, then my eddying theory is correct.

(This is all distinct, of course, from the not much addressed yet assertion of mine that centrifuging creates the eye in the first place; I'm not certain yet if anyone disagrees with that.)

[SkeetoBite]

Logorrheic postulations provide little comfort and no guidance to the unhappy recipients on the business end of this:



The inhabintants of this fine public forum, which you have graced with your presence and knowledge are forced to attend your dissertations with lexicon firmly in hand, lest they be left wondering... "Doth his words exceed our ability to comprehend? Further, whence did he come, seeking to eviscerate our pro mets?"

Pssst, nobody really talks like that anymore Its 2005.

[Mattie]

Mike18xx, whoever you are - take this to a debate forum - the majority of these people could care less about how and why at the time a storm is close to landfall - we are more interested in the where and when. AFM and the rest of the professional mets have been around here and we rely on them for updated insight, so if you wouldn't mind taking your meteorolgy debates to another forum, it would be greatly appreciated.

Yours truly,

[Wthrman13]

Mike18xx, whoever you are - take this to a debate forum - the majority of these people could care less about how and why at the time a storm is close to landfall - we are more interested in the where and when. AFM and the rest of the professional mets have been around here and we rely on them for updated insight, so if you wouldn't mind taking your meteorolgy debates to another forum, it would be greatly appreciated.

Yours truly,

Actually, I am quite enjoying this exchange, and I do feel it belongs in this forum (it is Talkin' Tropics after all, and that's what we are doing . ) I'm currently looking in more depth into this, as it is quite interesting. I will post more soon...

[Mattie]

That''s cool Wthrman13, and I agree that all this deserves equal time - but the topic of this conversation was not a debate topic - rather "Emily looking mucy better on SAT PICS.". . . which is not what you get when you read this post. I think this would be a great topic discussed elsewhere outside of this topic heading.

[mike18xx]

Pssst, nobody really talks like that anymore Its 2005.

"Wassap, bro!" (Is that better? )

[Wthrman13]

That''s cool Wthrman13, and I agree that all this deserves equal time - but the topic of this conversation was not a debate topic - rather "Emily looking mucy better on SAT PICS.". . . which is not what you get when you read this post. I think this would be a great topic discussed elsewhere outside of this topic heading.

Fair enough. I will start a new thread shortly to continue the discussion.

[SkeetoBite]

Pssst, nobody really talks like that anymore Its 2005.

"Wassap, bro!" (Is that better? )

Indeed. It will take more words, but everyone will benefit.

[mike18xx]

Fair enough. I will start a new thread shortly to continue the discussion.

Please populate it with the relevent posts here.

(I've said my piece, however, and shan't dwell on it much more, though there may be infrequent redirections to the "How scientists would resolve disputes like this" post.)

[tailgater]

sorry I got to ask . I ve' always been taught (in the little schooling I've had ) that the air in the eye sinks. BUT what confuses me why, if it has the lowest pressure. High pressure air sinks: low pressure more lift. Please continue this discussion I'm learning more here than I ever did in those classes.

[Air Force Met]

sorry I got to ask . I ve' always been taught (in the little schooling I've had ) that the air in the eye sinks. BUT what confuses me why, if it has the lowest pressure. High pressure air sinks: low pressure more lift. Please continue this discussion I'm learning more here than I ever did in those classes.

First...remember the low pressure is at the surface but there is high pressure aloft. Second...high pressure air does not necessarily sink...it diverges. Low pressure air does not necessarily rise...it converges. The point at which rising air stops converging in the low and starts to diverge with the high above it is called the level of non-divergence...or LND. IN the tropics...upper level lows actually create an area of descending air. Remember...in lows, air converges...and in the upper levels...when air converges...it has no choice but to descend. High pressure diverges. In the low levels...diverging air leads to downward vertical motion...but in the upper levels...diverging air leads to upward vertical motion because the vacated air leaves lower pressure...and the atmosphere wants to be in balance...so air rises from the lower levels to fill it (it certainly can't come from above).

Remember the hurricane is a low at the surface and a high aloft. Converging air begins to diverge at the LND (the point where the air is moving straight up...not going cyclonically or anticyclonically).When it hits the tropopause...it becomes more dense than the air around it...because the trop is where the atmosphere begins to warm again as you ascend. Remember air is rising in the eyewall and that is a circle. There is no rising air in the eye...but the eyewall. When that air rises and hits the trop...it can't go up...so most of it goes out...but some of it goes inward. That air converges...and remember upper level converging air sinks. This is just my opinion and that of the HRD/NHC/etc....and could be wrong.

Low pressure in the upper atmopshere cannot lift...it must sink (where could it lift too?). When I have forecasted in the true-tropics...places south of 15N and north of 15S...I have relied on a 200mb chart and a 925mb chart to find out if there was convergence at the sfc and divergence aloft. These were usually data limited areas and this is all I had. IF I had those set of ingredients, I would look for showers. IF I had convergence aloft and divergence at the sfc...I would look for clear/partly cloudy. The only rising air associated with lows are areas of low pressure below the LNC. The only sinking air associated with highs are those below the LND. Above the LND...lows sink air and highs pull it up. There are troughs of low pressure in the upper levels that cause rising air...but that is because they are divergent in one area or another. Closed lows converge air...closed highs diverge it.

Hope this helped.

[mike18xx]

Eye mechanics discussion continued here: http://www.storm2k.org/phpbb2/viewtopic.php?t=68640

[tailgater]

Thanx I kinda feel stupid that I didn't realize some of those points but I'll ask one more this LND region, where is at 500 mb 850 mb or does it vary?