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The journal article is many pages long. Surely there is more information available. Jdorje 19:53, 9 January 2006 (UTC)
How about a few satellite pictures to describe this type of hurricane?
I'm no meteorologist, but to me the logic of annular hurricanes seems fairly simple.
In an average hurricane, there is a pretty even wind gradient between the eyewall (which has the strongest winds) and the outermost rainbands (which have weak winds but are still tropical in nature). As time passes, assuming the storm continues to be powered energy will be transferred outward from the eyewall into the outer rainbands. After the storm passes peak intensity, the eyewall will weaken quickly as it goes through eyewall cycles. This transfers kinetic energy (or angular momentum) into the outer rainbands, speeding them up. Thus it is not necessarily the case that a drop in eyewall winds corresponds to a drop in the destructiveness of the hurricane, if it just means that energy is being distributed over a larger area.
An annular hurricane has few or no outer rainbands, and the area covered by thunderstorms all has high winds. With no "outer rainbands" to speak of, there can be no eyewall replacement cycles and no way to transfer energy outward from the eyewall. Thus, after passing peak intensity these storms do not naturally "flatten" and only weaken as they lose energy to friction with the surface.
Someone added that Katrina, Emily, and Epsilon were annular hurricanes. I removed this since it needs to have a source. However, Katrina in particular is the exact opposite of an annular hurricane. It had hideously huge amounts of outer rainbands, and as it went through its eyewall replacement cycle just before landfall a massive amount of energy was transferred from the eyewall (which therefore weakened tremendously) to the outer rainbands. The end result was a giant massive hurricane.
It's also surely the case that "annular" is not just a characteristic, it is a range. You can't just say that a storm has or does not have outer rainbands, it is always a question of how many it has. Among historical storms, likely candidates for annular hurricanes are those that were small: Camille, Andrew, Charley. Among 2005 storms, I think you look on satellite and radar for storms that look like donuts: a massive eyewall and not much else. Just based on the radar images I saw, I'd guess Ophelia and Wilma (only after crossing the Yucatan Peninsula) are likely candidates.
— jdorje ( talk) 20:08, 25 February 2006 (UTC)
Here is an IR loop of Daniel, showing the classic 'donut-ring' convection typical of annular hurricanes ( [1] from the Unisys Weather website [2]). This would make a great addition to the article.
I'm no expert at uploading images so if anyone can help, please do. Thanks! Pobbie Rarr 02:05, 22 July 2006 (UTC)
If someone could find a good Infrared image of an Annular hurricane, that would be awesome. Runningonbrains 19:58, 23 July 2006 (UTC)
The external link to the article has a few good images. Anyway, why has the Isabel pinwheel image been removed? I thought it looked awesome. Pobbie Rarr 20:43, 23 July 2006 (UTC)
I haven't read the entire journal article in order, but I can't really figure out where the "less than 1% of Atlantic and 3% of East Pacific hurricanes" bit comes from. The best match I can find is Table #4 of the Knaff article (with the same numbers repeated twice in the text), which lists 0.8% and 3% respectively for Atlantic and East Pacific for how many storms have all 8 environmental conditions conducive to the formation of an annular hurricane. I think I am going to change this unless someone finds the source for the statement as-is. — AySz88 \ ^-^ 00:56, 24 July 2006 (UTC)
From what I have seen and heard, Hurricane Epsilon was indeed an annular hurricane. Annular hurricanes are known to be able to survive in conditions that would flatten a normal hurricane, showing very little variation in strength. Epsilon was able to persist for days on end with very little variation in its strength, and actually if you look at some videos of it, you can see where there were very few outside rain bands on it, it was a small storm, and there was never and eye wall replacement cycle. However, most, if not all, annular hurricanes are only annular for a portion of their life, like in the case of Epsilon. Towards the end of its life, you can see where the outflow began to form, and later that night, the storm weakened to a minimal tropical storm, and later dissipated that day. —Preceding unsigned comment added by 74.160.83.146 ( talk) 22:59, 26 April 2011 (UTC)
Is there any typhoons that has a structure similar to an annular hurricane? Irfanfaiz 13:29, 24 July 2006 (UTC)
From what I have seen and heard, Hurricane Epsilon was indeed an annular hurricane. Annular hurricanes are known to be able to survive in conditions that would flatten a normal hurricane. It also showed very little variation in strength. Epsilon was able to persist for days on end with very little variation in its strength, and actually if you look at some videos of it, you can see where there were very few outside rain bands on it, it was a small storm, and there was never and eye wall replacement cycle. However, most, if not all, annular hurricanes are only annular for a portion of their life, like in the case of Epsilon. Towards the end of its life, you can see where the outflow began to form, and later that night, the storm weakened to a minimal tropical storm, and later dissipated that day. —Preceding unsigned comment added by 74.160.83.146 ( talk) 23:00, 26 April 2011 (UTC)
Some of the conditions associated with annular hurricanes are: An intensity 85% or greater from their theoretical maximum potential intensity, weak wind shear from the east or southeast, a cold east wind at a high altitude (the 200 mbar pressure level), near-constant sea surface temperatures between 25.4 °C and 28.5 °C, and lack of relative eddy flux convergence at the 200 mbar pressure level, relative to the storm.
Stuff like this means very little to the layman. Can someone rephrase the technical mumbo-jumbo into prose that most people can understand? Runningonbrains 04:52, 26 July 2006 (UTC)
Would creating a list of annular hurricanes at List of annular hurricanes be feasible? I think it would be interesting to know that, so would it be possible for it to be done, or does the "significant annular hurricanes" section pretty much cover all of the known ones? bob rulz 02:42, 27 July 2006 (UTC)
Although we obviously don't know for sure why certain hurricanes become annular, perhaps this NHC discussion of Hurricane Daniel might help. It anticipated Daniel becoming annular:
FORECAST ENVIRONMENTAL CONDITIONS OF LIGHT EASTERLY SHEAR AND SLOWLY DECREASING WATER TEMPERATURES BELOW 28C ALSO SUGGEST THAN THE HURRICANE COULD BECOME AN ANNULAR-TYPE SYSTEM OVER THE NEXT DAY OR SO.
Basically, shear was light in the direction of Daniel's motion and SSTs were mildy favourable for sustenance. I wonder if the NHC will devote a section to annular hurricanes some time soon. Pobbie Rarr 15:26, 24 August 2006 (UTC)
While I do agree the current image is pretty good, the one added by User:Good kitty ( Image:Isabel-eyewall-091203.jpg) was better, showing more detail of Isabel's classic annular structure, and without the distracting text imbedded in the image itself. Thoughts? - Runningonbrains 04:37, 28 September 2006 (UTC)
That seems like an awful lot of examples for something that's only supposed to happen once every 100 hurricanes (1% frequency). Mdotley 16:49, 3 October 2006 (UTC)
OK, I reread it again, and it doesn't actually SAY they occur at that frequency, but it darn well implies it. If that's not what we want ppl to take away from that paragraph, then the relationship between favorable conditions and actual annularity needs to be spelled out a bit more, (even if it's to say that we don't know exactly how they're related). Mdotley 16:52, 3 October 2006 (UTC)
MICROWAVE IMAGERY HAS SHOWN AN IMPRESSIVE ANNULAR CYCLONE WHICH DEEP CONVECTION HAS BECOME COOLER AND EYE WARMER IMAGE AFTER IMAGE (AMSU 0909S)
Hi. Were Typhoon Nida (2009) and Hurricane Wilma annular hurricanes? Thanks. ~ A H 1( T C U) 22:20, 31 August 2010 (UTC)
Could it be listed here as an annular hurricane? It looks like one to me, and it would explain why one would persist in the South Atlantic and not weaken. I've always thought of Catarina as similar to Epsilon in form. Cyclone Catarina UltimateDarkloid ( talk) 19:46, 14 November 2010 (UTC)
I have added several hurricanes that were considered annular according to and article in the AMS Journal called 'Objective Identification of Annular Hurricanes' and I don't know how to cite it on wikipedia. Stormchaser89 ( talk) 5:45, 21 July 2011 (US Central)
In the article: "Hurricane Epsilon of the 2005 Atlantic hurricane season had a similar structure to an annular hurricane, which partially explains the storm's longevity in the face of unfavorable conditions." -- I don't think it really "explains" anything, since, as far as I can see, it's not exactly clear why annular hurricanes form or persist like they do. 172.130.139.99 ( talk) 22:35, 3 August 2011 (UTC)