Keith234
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How could Hurricane Alex devlop in an area that is above 5 degrees of the equator? The coriolis force is not nearly as strong at 30 degrees than at 5 degrees above the equator, right.
Also does the reason that Hurricane Alex formed in a area that was partially sub-tropical, explain the reason for it setting the record books as the strongest hurricane at the highest latitude? In another words is there a correlation between where a hurricane forms and how far north it can survive?
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"I became insane with horrible periods of sanity"
Edgar Allan Poe
Edited by Jason234 (Tue Aug 24 2004 06:20 PM)
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LI Phil
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>>> How could Hurricane Alex devlop in an area that is above 5 degrees of the equator?
Not sure where you're getting your data but Alex developed around 30N. That's 30 degrees above the equator, not five. You might want to recheck your "source." 
Alex
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Keith234
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Yes, your right it formed at 30 N, I got to check my posts before I post them. The overall question remains the same though how could a hurricane devlop in a area 30N of the equator? I thought that the Coriolis force gets weaker as you get further away from the equator.
And my other question from the previous post remains the same.
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"I became insane with horrible periods of sanity"
Edgar Allan Poe
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Clark
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The Coriolis force actually gets stronger as you move away from the equator. Tropical systems could technically form at 80°N if the sea-surface temperatures and other conditions were favorable (which they never are).
The Coriolis force is too weak near the equator to allow a storm to form. It varies with latitude according to the equation f = 2 * omega * sin(latitude), where f is the Coriolis force, omega is a rotational constant of the Earth (equal to 7.292x10^-5 radians^-1, if I recall correctly), and the latitude is something like 45 degrees. The sin of 0 degrees is 0, making the Coriolis force non-existant at the equator. At 5°N, f is only equal to about 1.27x10^-5 -- whereas at 45°N, it is a full ten times larger.
In layman's terms, the Coriolis force is too small to support a circulation at low latitudes due to the force balance between it and the pressure gradient force (the magnitude of which is determined by the difference in pressure between two points; also note that there are other forces besides these two in consideration, but these are the predominant ones). It also helps to explain why storms become deflected to the right of their motion - i.e. recurve - with time & increasing latitude.
(Footnote: I was about to tackle this one, but I'm sure glad that you did  . It is also a primary factor in the circulation of storms, i.e., counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. In a classic model, your answer is correct, but in the real world the actual 'zero' force point resides at about 5N in the northern hemisphere winter and at about 10N in the northern hemisphere summer - because of the tilt of the earth's axis. Which explains why some of these low latitude Cape Verde systems take such a long time to spin up. A system that emerges off the African coast at 9N has a much tougher time of it than one that emerges at 12N if other factors are otherwise equal. Thanks for the superb answer.)
ED
Edited by Ed Dunham (Tue Aug 24 2004 08:10 PM)
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Keith234
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Wow, thanks! The source of where I read my information was misunderstood. What now makes even more sense is the explantion of why tropical cyclones only form in the summer, besides the fact of the the reduced wind shear and the increased surface temp. at the ocean, I knew that the rises northward to about were the cape verde islands, and now that the coriolis force actually is greater than 0, makes troughs (tropical waves) that come off Africa, enough spin to become a hurricane. Thanks again.
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"I became insane with horrible periods of sanity"
Edgar Allan Poe
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LI Phil
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Clark & ED, both great responses. I'm not making light of this, but in fact the Coriolis affects the "movement" of water in every regard. If you were to run a faucet or flush a toilet in the southern hemisphere, it would "go down the drain" in clockwise fashion, as opposed to the northern hemisphere, where hurricanes as well as water drains rotate in counter-clockwise fashion. An excellent recent example was Hurricane Catarina in Brazil...spun clockwise...quite different to what we are used to seeing up here. Also, any of the Southern Hemisphere (Australia et al) storms. Pretty amazing scientific phenomenon, huh?
If one runs water down the drain at the equator, does it rotate? (Serious question).
Cheers,
LI Phil
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Keith234
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That's a pretty interesting question, but if it's zero at about 5 degrees north than at the equator it has to have some value. I guess it depends on the season your in.
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"I became insane with horrible periods of sanity"
Edgar Allan Poe
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Ed Dunham
Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017)
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If one runs water down the drain at the equator, does it rotate? (Serious question).
Yes it does - at random in one direction or the other. Keep in mind that Coriolis is just one factor that influences rotation. There have been a couple of rare clockwise spinning tornadoes noted in the southeast U.S., and clockwise spinning waterspouts have been seen in the Fllorida Keys.
ED
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Keith234
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Isn't there a term that describes a pressure blance with the coriolis force, something with a G? Also I have been reading about a typhoon that formed at the equator, Typhoon Wayne, was this because of geography, or is an unkown science thing?
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LI Phil
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Geostrophic Wind: winds balanced by the Coriolis and Pressure Gradient forces.
An air parcel initially at rest will move from high pressure to low pressure because of the pressure gradient force (PGF). However, as that air parcel begins to move, it is deflected by the Coriolis force to the right in the northern hemisphere (to the left on the southern hemisphere). As the wind gains speed, the deflection increases until the Coriolis force equals the pressure gradient force. At this point, the wind will be blowing parallel to the isobars. When this happens, the wind is referred to as geostrophic.
Winds in nature are rarely exactly geostrophic, but to a good approximation, the winds in the upper troposphere can be close. This is because winds are only considered truly geostrophic when the isobars are straight and there are no other forces acting on it -- and these conditions just aren't found too often in nature.
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Keith234
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Thanks for the anwser, it seems like you guys (Clark,ED, and LI Phil) know everything about weather, no wonder your mets. I guess I'm a yankee for now  
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"I became insane with horrible periods of sanity"
Edgar Allan Poe
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LI Phil
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Well, Ed is a lifetime met, and Clark, I believe is on his way to being one, if he is not one already. Moi, I'm just a weather enthusiast but I've learned more from reading (and eventually posting) on these boards than you could imagine. Stick around...you will too.
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Clark
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Well, depends on how you want to classify it - I've got the B.S. in meteorology (no comment on that...haha), but still working at future degrees. But, I've learned a lot here too...especially on forecasting and predicting these things than I've learned in classes, where it's almost all theoretical, especially in the tropics.
Quick reply to danielw (who I can't reply to his PM from this Coriolis subject because he's exceeded his quota...oops...plus it might be relevant to all, as it's on rex blocking.) I usually don't like doing this, but don't want to give the impression of being ignored:
"A Rex block is where you have a high pressure system over (i.e. north of) a low pressure system. What happens is that anything that approaches the broad ridge cannot simply ride up and over, as the flow around the low prevents this. Systems cannot go through either as there is no steering current to push them forward (a col region gets set up between the high and the low). Thus, until a strong enough system comes through to break up the block or either the high or the low weaken (it's usually the latter), you get a whole lot of nothing."
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