tb_hurricane
Unregistered
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I remember gabrielle pretty well...had very intense wind gusts to near hurricane force over the bay briefly...destroyed marinas along the west coast...
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Notathome
Unregistered
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Wow Terra, I'd love to know what you do for a living. I am assuming you are not a meteorologist but are some kind of scientist because you doing some advanced thinking on Atmospheric Science there.
I could try to explain it to you but I would need an hour, a good dynamics textbook for re-inforcement and some NoDoz to keep you awake.
The bottom line is that there is a relation but it is not a constant relationship. It's a lot to do with upper air dynamics and global patterns. Basically at the same level, if the temperature is different than so will be pressure. If the temperature dropped than it's likely that the pressure will be higher, but not in direct realtion and not due to the reduction in temperature.
Look, I took three semesters of dynamics and it's still fuzzy sometimes. I hope this answered your question.
At least I tried!
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Colleen A.
Moderator
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Posts: 1432
Loc: Florida
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Well done! That's a pretty cool picture, too.
To be very honest with you, unless the models start changing their ideas and/or the doesn't see any reforming of the center, I don't know that we're right or wrong.
As JK explained to me last night, I can't use the WV loop to find the center, but from everything I CAN see, it appears to ME that the center may be trying to reform further east and under the convection. It's easier for the storm to do that - like they have brains or something that tell them:
"Gee whiz, ya know....if I move over HERE, I can really get my act together, miss the shear altogether and get all four quadrants fired up. Not only will I throw off all the models, ticking off Frank P. up there in Mississippi, but everyone in Florida will be running around like raving lunatics wondering what I'm gonna bring them. So yeah, I'll move to the right.
Or NOT!"
See, this is what happens when a storm doesn't act like you want it to. It makes your brain all jiggly and jello-like. 
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You know you're a hurricane freak when you wake up in the morning and hit "REFRESH" on CFHC instead of the Snooze Button.
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damian
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I remember Gabrielle too. It came through in the early morning, although i thought it was closer to Venice than Port Charlotte. The wind really whipped through Bradenton (my friend had a gauge that measures wind speed and that thing said the wind was constant 65 MPH for about 3 minutes). Anyway, i always thought it was a minimal cat 1 when it hit, but it was in between recons and we were told it was a TS. I remember TS Marco years ago and that was nothing campared to Gabrielle.
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wxman007
Meteorologist
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Loc: Tuscaloosa, AL
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The chatroom is open, look to the chat link to the left, or if you know your way around IRC, connect to irc.flhurricane.com:7000 and join room #flhurricane. I'll be there and we can roundtable a bit if you all want to.
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Jason Kelley
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Terra
Storm Tracker
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Loc: Kingwood, Texas
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Quote:
Wow Terra, I'd love to know what you do for a living. I am assuming you are not a meteorologist but are some kind of scientist because you doing some advanced thinking on Atmospheric Science there.
I could try to explain it to you but I would need an hour, a good dynamics textbook for re-inforcement and some NoDoz to keep you awake.
Nah, you wouldn't need NoDoz, as I am such a nerd that I would enjoy the three semesters condensed into an hour. I suspected I would be told that it was related, but not in a linear manner, I was just hoping my answer would be something that didn't require differential equations. I find it interesting that a drop in temperature would cause an increase in pressure... seems backwards... I'll try another argument besides the ideal gas law.... if temperature decreases, relative humidity would increase (provided water vapor remained constant). This would cause condensation to occur (if the RH reached saturation) and would actually lower the water vapor concentration in the atmosphere.. now, I'm sure, since water vapor is only 0-4% of the total atmospheric composition that the effect would be negligble, but how could the pressure be higher? Man, I'll never get it!
As for me, I am an analytical chemist that stumbled into an atmospheric chemistry group for graduate school, as I wanted to go to Greenland. We looked at chemical reaction mechanisms (focusing on tropospheric ozone, actually), and while I had to take one atmospheric chemistry course, and do number density/scale height calcs for some of my gas-phase computer models, I didn't learn too much about how the atmosphere works... does that make sense? Now I teach chemistry and Earth science and I find every semester, I teach more and more about the atmosphere and meteorology. In fact, last semester, I actually took a stab at teaching adiabatic lapse rate to my 100-level survey class... not sure how it went over, but I think they caught on.
Anyway, enough about me... who are you Mr./Ms. Not-At-Home?
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Terra Dassau Cahill
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mysticalmooons
Weather Watcher
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Posts: 30
Loc: rockledge, fl
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hehe I Terra won that one notathome
dont even try to response, um quite pointless at this point. lol
lol 
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Colleen A.
Moderator
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Loc: Florida
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Sounds good!
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You know you're a hurricane freak when you wake up in the morning and hit "REFRESH" on CFHC instead of the Snooze Button.
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Tazmanian93
Weather Master
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Posts: 495
Loc: Tampa
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Evening all, been away since 5pm EST, anyone wanna give a quick and dirty update for me, she looks a bit haggered. Also, where did 91L go??????
Edited by Tazmanian93 (Fri Jun 10 2005 02:31 AM)
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mysticalmooons
Weather Watcher
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Posts: 30
Loc: rockledge, fl
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damn it java wont run right
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wxman007
Meteorologist
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Posts: 617
Loc: Tuscaloosa, AL
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Try downloading MIRC....
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Jason Kelley
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Tazmanian93
Weather Master
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Loc: Tampa
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Not sure of your OS, 2 days in a row w/ JAVA issues, get a hold of the HD for your system, gotta have JAVA for this
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Don't knock the weather; nine-tenths of the people couldn't start a conversation if it didn't change once in a while.
Go Bucs!!!!!!!!!
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Ed
Edited by Tazmanian93 (Fri Jun 10 2005 02:33 AM)
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Clark
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Terra -- with weather systems, we typically use what is called the hydrostatic approximation. It comes out of Newton's second law and a force balance diagram, essentially, and isn't specific to just meteorology. It states that the change in pressure over a change in height is equal to the negative of the gravitational constant times the density. You can plug the ideal gas law into this equation (for density; p = rho*Rd*Tv) to get a relationship with regards to temperature. Further manipulation is possible until we get to something called the hypsometric equation. I won't go into the full details here, though.
This equation allows us to use thickness principles -- essentially, how far of a distance is it between two pressure levels -- in conjunction with atmospheric laws to understand the temperature structure of cyclones. Low pressure systems can have either warm or cold cores, where the temperature in the center of the system is either warmer or colder (respectively) than that outside the center. How these cyclones vary in intensity with height comes from this equation and shows how a warm core surface cyclone must weaken in intensity with height -- as we see with hurricanes. That's but one of many examples -- there are lists around in meteorology texts that deal with many more -- but the jist of everything is that with a cyclone, the strength of the warm or cold temperature anomalies will determine how far the pressure falls.
Note that in a simplified scenario, we can use the ideal gas law; but in reality, the more applicable equation is the moist gas law. Nevertheless, the implications are about the same.
Hope this isn't too far out there...
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Current Tropical Model Output Plots
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lawgator
Weather Hobbyist
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Loc: E C Fla.
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Quote:
Note that in a simplified scenario, we can use the ideal gas law; but in reality, the more applicable equation is the moist gas law. Nevertheless, the implications are about the same.
Hope this isn't too far out there...
Okkkaaaayyyyy. The "simplified" ideal gas law. But of course!!!
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lawgator
Weather Hobbyist
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Loc: E C Fla.
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Riddle me this.
The 5 p.m. forecast path seems to already have built into it an initial west of north path, then more poleward, then more east after landfall around the Ala-Miss border. If the storm is at this point moving north (rather than west of north as in the 5 p.m. path), does it not follow that even if the ridge builds in, the speed is correct, blah blah blah, landfall must be east of the projected path? And, if so, it would seem that the longer it moves poleward before moving to the left a bit, the further east the projected landfall would have to be.
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Clark
Meteorologist
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lawgator -- I didn't say the simplified ideal gas law; I said that it simplifies the interpretation of things. The ideal gas law is for just that -- an ideal gas. The atmosphere & its gases doesn't always work under "ideal" conditions...
As to your follow-up question, you are correct. I'm not sure why the track was shifted a bit further east, but it's a smaller-scale repeat of what we saw to some degree last year. Only time will tell how it plays out, but I personally think the 11a track is more representative than the 5p track. But trust the professionals, all things considering.
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Current Tropical Model Output Plots
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mysticalmooons
Weather Watcher
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Posts: 30
Loc: rockledge, fl
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mirc good, what channel?????????? to log into. I click on chat it connects asks me what channel to connect?
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Terra
Storm Tracker
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Loc: Kingwood, Texas
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I remember learning the ideal gas law in high school and then in college... then I took physical chemistry and was crushed when I learned that gases don't exactly behave ideally under normal conditions.... We learned how to deal with real gases and mathematically... that was just not fun. This is why I strayed far from physical chemistry!
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HCW
Storm Tracker
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Loc: Mobile,AL
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A tropical storm watch will likely be required Friday morning for
portions of the north central U.S. Gulf Coast from southeastern
Louisiana eastward to the Florida Panhandle
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Over 4,000 members and now on a new server
http://www.hardcoreweather.com
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lawgator
Weather Hobbyist
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Loc: E C Fla.
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Thanks Clark. That explanation clears things up in the sense that originally I had no idea what you were talking about. Now, however, I am totally with you. Uhhhh. Not really. But I am a mere Gator and you live in Tallahassee. I figure you being physically closer to the supercomputer gives you a leg up on me in the smarts department. The only "gas law" with which I am familiar is the one where you are not allowed to get gas and leave without paying for it.
In all seriousness, I agree with your assessment on the official forecast track going back right. Just watched the IR floater and "center" (such as it is) sure seems significantly east at this point of where they thought it would be.
I have a tee time Sunday. Cart path only or mask and snorkel?
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