Talk:Tornado/Archive3

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This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

Contents 1 Removing the climatology section 2 Modified 3 Frequent tornados in north western Europe? 4 Radar tool 5 2006 Tornado Outbreak 6 Funnel pressure attributed to Bernoulli´s principle? - Not! 7 Baby steps of improvement 8 Frequency of occurence 9 May 99 Oklahoma and other radar wind measurements 10 Prediction section cover forecasting? 11 Failed GA

Removing the climatology section

As the vast majority of this section is unreferenced, unfactual, or downright nonsense, I am removing it for now, with a notice to expand and improve. IMHO, it is better to have an incomplete article than a misleading article. I will comment out the text, so it can still be edited, but will not appear. Please do not add anything to this section without referencing a source (if you do not know how to properly cite pages, just put the URL in brackets like this: [http://www.referencepage.com] after your addition. I will be checking this page regularly, and I will format these links appropriately. -Runningonbrains 05:18, 14 August 2006 (UTC)

Modified

I modified the article, so 'Detection In the UK' and the United Kingdom subcategories became merged, and I corrected another spot [See history page]. --Typer Boy 20:53, 24 August 2006 (UTC)

Frequent tornados in north western Europe?

Could someone back up this claim (which appears in the very opening sentences of this article)?

Tornados rarely occur above 45 degrees latitude and are most frequently observed in the US, China, India and Bangladesh. But here in northwestern Europe tornados occur only very rarely as far as I know. For example here in the Netherlands the last whirlwind that could be classified as a tornado occured some 40 years ago. Unless this claim gets some credible backup I say it is best removed. Albester 13:07, 26 August 2006 (UTC)

You're incorrect - see for example NLM Cityhopper 431 flight about a tornado detected in Netherlands during last 40 years. NW Europe is moderately prone for tornadoes, nothing compared to US Midwest or Florida, but frequency is nevertheless greater than in most US states. Finland for example gets on average 10 waterspouts and tornadoes every year. --Mikoyan21 23:56, 19 September 2006 (UTC)

Damaging and even fatal tornadoes have been reported in Germany, Poland, Israel, and the UK just this year, just off the the top of my head. Multiple tornado events have also occurred in the Netherlands (and other areas of western Europe). See: List of tornadoes and tornado outbreaks for some more significant events worldwide over the last several centuries (also check out the sources at the bottom). Also, consult above threads for European tornado climatology discussion. Particularly look at Dotzek (2003). For more information, check out the European Severe Storms Laboratory (ESSL). Evolauxia 05:13, 20 September 2006 (UTC)

From what I understand, the confusion arose from a difference in translation of the word tornado. Apparently, in the Dutch language, there is more than one word for tornado, and our word tornado literally translates into Dutch as a particularly violent tornado. Violent tornadoes are rare in Europe, but tornadoes in general (in the American definition) are relatively commonplace. -Runningonbrains 05:29, 20 September 2006 (UTC)

I've noticed this tendency too (as well as the media's penchant for using "mini-tornado" even in cases of significant supercellular tornadoes). Most of the smaller tornadoes are landspout and waterspout type events, which are differentiated by the US/UK (et al) but categorized as tornadoes. The Dutch and German researchers include these as tornadoes as is standard practice in science as far as I know; there may be a difference between the scientific literature and discussion (with which I'm more familiar) and culture at large/media. The UK climatology used for the claim of highest tornado frequency per area includes the smaller tornadoes. The research I cited (for the Netherlands claim and for Western Europe, generally) does as well, so *is standardized*. The bottom line is significant tornadoes occur all across Western Europe every year, and although the threat isn't that of parts of the US (and Bangladesh/India, etc.), occasionally there are very strong events too (regardless, there are damaging tornadoes and at least a few fatalities annually). Evolauxia 11:54, 5 November 2006 (UTC)

Check out this page: Tornádo mezi Brnem a Blučinou dne 20. 7. 2001, and as you can see from the main page Tornadoes at the Czechia and Slovakia, that's not too rare. Strong tornadoes occur almost every year in the Czech Republic and tornado outbreaks are common. That's just one country, others in Europe are similar (including western and northwestern). Evolauxia 03:43, 13 November 2006 (UTC)

heres some evidence that they do occur relatively frequent in the UK and i would suspect its the same for the rest of north western europe - http://news.bbc.co.uk/1/hi/england/london/6217514.stm

Radar tool

I've gone a little mad with a new shiny toy I've found on the NCDC site, see the wikiproject threads for more info (Wikipedia talk:WikiProject Meteorology#Radar toy/Wikipedia talk:WikiProject Tropical cyclones#Radar toy). This image is just a quick one I managed to make up of a typical tornado in Kansas. It shows the classic hook echo forming and dispersing quite nicely.--Nilfanion (talk) 14:38, 30 August 2006 (UTC)

2006 Tornado Outbreak

The news outlets are reporting that a major tornado outbreak is going on. Detailed reports are on the Weather Channel and is website right NOW. Major damage has already been reported, I do not know if there is any casualties, deaths @ this time. The outbreak is going on RIGHT NOW. Martial Law 00:58, 23 September 2006 (UTC)

Funnel pressure attributed to Bernoulli´s principle? - Not!

I suggest the reference to Bernoulli's principle for causing the low pressure of the tornado funnel is removed. It's really a longer story! —The preceding unsigned comment was added by 213.64.177.93 (talk • contribs).

I'm not exactly sure what you're referring to. I'm pretty sure the text thats there is completely true... -Runningonbrains 21:43, 8 October 2006 (UTC)

Actually, the comment above is essentially correct. The cause of the extreme low pressure inside a tornado is due to many factors, only one of which may be attributed to the Bernoulli Effect, as mentioned. Other effects include the rotation of the fluid itself, which must be balanced by a corresponding inward directed pressure gradient force (cyclostrophic balance) or the vortex will soon dissipate. Thus, there must be a dynamically-induced pressure minimum inside the tornado. This is actually a fundamental property of any rotating fluid. Not only that, but there is also a contribution (albeit smaller) from the buoyant updraft of the parent thunderstorm itself above the tornado, which causes a drop in pressure relative to the surroundings immediately below the base of the updraft. I'm thinking about expanding the section in question to include both effects (I would link to the article on cyclostrophic balance, except that it doesn't exist!), but I'm a little leery of doing so until I can provide a couple of references. Would such an edit require references, do you think? Wthrman13 03:15, 22 October 2006 (UTC)

Baby steps of improvement

I can see it is going to take a while to get this article to a point where it can be recommended for GA. Much of the data needed internationally is just sketchy, though it is more abundant than implied in the article before the edit. Two of the expand boxes had to be removed...how much can anyone write in a section labelled "time of occurrence?" Most of my changes related to who runs the severe weather programs in several countries, as well as their recent efforts to create exhaustive databases, and some climatological aspects. Thegreatdr 20:13, 25 October 2006 (UTC)

Well, before I looked here I was going to nominate it for GA given your/my recent edits. The way I see it, if we nominate it now, it will take a week or more for anyone to even look at the article, given the backup in the natural disasters category. In that time I hope I can at least justify removing expand notices, and it should pass easily. -Runningonbrains 08:08, 26 October 2006 (UTC)

Frequency of occurence

I will soon be expanding this section. Here are two good links if anyone else wants to work on it in the meantime. [1] [2] -Runningonbrains 17:52, 2 November 2006 (UTC)

May 99 Oklahoma and other radar wind measurements

The popularly quoted 318 mph number is incorrect or at least misleading and Wikipedia should strive to be as accurate as possible. That was an upper bound that Dr. Wurman let slip out in the frenzy of the moment and the media immediately seized upon it. The Fujita wind speeds are so theoretical that he didn't even think about 318 mph being one mph from F6. In personal communication with Wurman, he said the calibrated measurement was 301 ± 17 mph lasting less than a second in a small area on the edge of the circulation. The vehicle was moving and the measurement was 30 m AGL. For now, I use the CSWR page (Wurman's group) as my source; more recent and superior to USA Today. That measurement is 301 ± 20 mph.

The article is correct that only near surface wind speeds (~10 m AGL) and damage are taken into account in ratings. I know of only one tornado so far that was rated based on a radar measurement. This is mostly due to sparsity of radar measurements, poorly understood correlation of winds to damage (and innumerable problems with damage itself), and issues of deriving lower height measurements from above observations. A problem with radar measurements, particularly close proximity scans, is debris scattering increasing reflectivity. Another problem is the (near) momentary nature; official wind speeds are given in various vector over time values. For example, 1 s, 3 s, 10 s, 1 min, or 10 min periods of mean, maximum, or whatever value. Single DOW measurements are means taken in a small fraction of a second and are much shorter interval than official measurements. It is highly likely that very brief, very high wind speeds (quite possibly well over 320 mph) occur over a very small area in tornadoes (one would expect this from physics and it has been modeled), but this is too small to count being below official measurement intervals, having no real effect on anything, and not necessarily being indicative of the strength of the tornado. Sometimes underestimating wind speeds is that scatterers (debris can cause over- or underestimates) move slower than actual air motion (rapid acceleration and angular acceleration of subvortices especially skews things); and the measurements of a mean per volume could miss gusts of too small spatial dimensions to sample.

Our article's reference of 100 m AGL wind speeds being higher than surface requires tweaking. Tornadoes vary, as does their wind field structure and dynamics, but in observations and numerical modeling, maximum wind speeds occur in a near surface layer that is slightly above the surface but below 100 m or even 70 m. This is due to interaction with the ground and is particularly true for strong tornadoes. Wurman et al speculate that this boundary layer was below 50 m and not sampled in the Moore tornado. Evolauxia 03:31, 10 November 2006 (UTC)

The Red Rock Wikipedia article mentions a wind speed range, which is excellent, but it's lower than the one with which I'm familiar. It was something like ~270 to ~286 mph with ~275-280 mph the best estimate and that's where you get the 286 mph number that is popularly quoted. Given the units of m/s and inclusion of range of error, it's probably from a scientific source however it's unsourced. I'll leave those measurements for now, but it needs a citation.

FYI, a plethora of info is contained in the 3 May 1999 Tornado Outbreak Special Issue of Weather and Forecasting.

See, I definately did not agree with the 318 number (I knew it was 300 or so with a range) but for the life of me I could not find a source that stated otherwise. Thats actually the first I've heard of studies on where the maximum winds in a tornado occur...do you have links to further info on that? -Runningonbrains 05:26, 10 November 2006 (UTC)

It possibly was 318 mph or even higher, but of course you go with the measured number not whatever bound you like (the media incessantly quote the upper bounds of respective F-scale categories), it's also possible it was 280 mph. Curiously, Wurman's site repeatedly has a discrepancy in the conversion of SI to Imperial units that is well above that attributable to rounding errors. For now, I'll stick with the inferior imperial system but would not oppose going with the m/s values and converting from that ourselves. There was debate on where the maximum wind speeds occur, generally it was believed to be several hundred feet AGL (though Hoecker (1970) published photogrammetric studies from as early as the 1957 Dallas tornado) until enough mobile radar measurements showed that it was in a near surface boundary layer. It was discovered within the last few years that very strong winds can occur even a few inches above the surface. It's not known how common that is. As for a source, there are various, especially in papers on radar observations and tornado structure, dynamics, and morphology (many of which involving numerical modeling). A relevant one doubly pertinent to this discussion (though obviously not written specifically on wind field structure in general) is:

• Burgess, et al (2002). "Radar Observations of the 3 May 1999 Oklahoma City Tornado" [3]. Weather and Forecasting, 17 (3).

Evolauxia 06:25, 10 November 2006 (UTC)

Prediction section cover forecasting?

Curiously, there is a section named prediction but it only lists agencies and organizations that make weather forecasts and warnings; nothing on how they do so. Surely there should be at least a basic overview of tornado forecasting. Conditions and ingredients, etc. The tornadogenesis section is slowing growing, it would be nice for it to be complimented with the basic process of prediction and favorable meteorological conditions. It will also integrate well with detection (a section that needs work as it would be enlightening on how warnings are issued) and other sections such as climatology. It doesn't necessarily have to be in the prediction section, though given the name it makes sense. Evolauxia 10:29, 10 November 2006 (UTC)

Definately all needed things. It seems like we're going to need a lot more subpages to make the article comprehensive and managable. -Runningonbrains

Failed GA

This article failed the GA noms due to having lots of stubby sections. This article also has alot of lists which need to be made into prose. There is also alot of empty space between sections and the pictures are all on the right side and unbalanced in distribution. Tarret 01:43, 18 November 2006 (UTC)