Talk:Beaufort scale

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I learned to use the beaufort scale in 1941 while plotting daily synoptic charts in the Army Air Corps at Kelly Field, Tx. This is very good.jonhays 00:35, 19 Sep 2003 (UTC)

Contents

[edit] Expansion/variation

Although metric measures are probably a better choice, should I also include the US Imperial measures? (ie: wave heights in feet 0, 0, 0-1, 1-2, 2-4, 4-8, 8-13, 13-20, 13-20, 13-20, 20-30, 30-45, and 45+) Also, there is a corresponding sea state scale, 0-9, which is common in North America due to its use in Bowditch and inclusion in Navy logs. - Amgine 18:44, 26 Nov 2004 (UTC)

I think the table can be extended according to section E of this document. Momoko

[edit] km/h as opposed to m/s

Is it common (and if so, where) to denote wind speeds in km/h? In my native Sweden, I have only ever seen m/s (and of course knots in nautical contexts). It may well be that in other parts of the world, km/h is used instead, but if not, I think the table should give values in m/s (first because it's the SI unit), knots, and mph. -- Jao 19:16, May 29, 2005 (UTC)

Of the three countries I've lived in, weather forecasts in two (Germany and Canada) use km/h, while one (Britain) uses the Beaufort scale itself. I've not seen m/s, although I'm sure it is standard in scientific contexts, and as you say in Sweden! I added km/h as I thought it would be more intuitively intelligible to the majority of readers; even if they're not familiar with wind measurements in km/h per se, most people will have some idea of what it feels like if you stick your hand out of the car window at 100km/h. I suspect anyone with a scientific inclination is capable of going to the article on knots and performing the relevant computation for themselves, but I certainly wouldn't be against adding m/s to the article as well. Best wishes, Cambyses 08:41, 30 May 2005 (UTC)

You have convinced me that km/h should stay. As to whether we could have a fourth measure, well, I won't go into that. It might become too much. -- Jao 10:01, May 30, 2005 (UTC)

In Bulgaria usually meteorolists are forecasting the winds in m/s, while news reporters on the TV are using km/h. Thus I am going to put both under single column in the Bulgarian version. -- Goldie 19:20, 24 September 2005 (UTC)

M/s is normally used in Denmark, as well, and Km/h is pretty much reserved for vehicle speeds. A scandinavian tradition, perhaps. I'd say m/s should definitely stay on the list, if nothing else, though; while it may be 'normal' for people to experience (strong) windpressure on the playful hand at high vehicle speeds, m/s seems more immediately applicable to the experience of windpressure on the whole body, and ideas of high fast you'd need to move (running) to keep up with it/ how hard work it is to walk against the wind.

[edit] Speeds

On, 17 June 2004 21:12 speeds were change to mean speeds. I feel that this may have been misunderstood by the user who changed them because the user added a less than and greater than value to the mean speeds on the high and low ends. Are the means speeds really needed? -- 03:19, 9 Jul 2005 (UTC)

[edit] Beaufort criteria for effects on sailing ships

Ought the criteria given by Beaufort, listed at both the Met and National Weather Service websites, be given here too? There does not seem to be room in the table, but maybe there is, and at the least it could be added in a separate table on this same page. - Centrx 18:34, 15 August 2005 (UTC)

I'd support that. PeteVerdon 12:09, 14 March 2006 (UTC)

[edit] Waves under hurricane?

I've always thought that there are big waves under a storm, but almost flat water under a hurricane, since the waves would be blown apart? Is that a myth, or? 83.93.224.223 12:24, 29 October 2005 (UTC)

Myth. Maybe in an extremely strong hurricane, but not in your every-day hurricane. - Cuivienen 02:38, 5 December 2005 (UTC)

[edit] Extension to Force 17

When was the scale extended? UK MetOffice said that the Beaufort scale was extended in 1944.[1] However, I've seen a few sources saying that it was extended in 1950's.[2][3] Which one is true? Momoko

The Nynorsk version of this page gives specific wind speeds for 13, 14, and 15. -- Evertype·✆ 11:49, 1 December 2006 (UTC)

[edit] Scale is a jpeg

I don't like that. So I changed it into text again. 218.168.213.149 05:33, 23 June 2006 (UTC)

[edit] "Table of degrees"

[4] would have it that there's a forerunner to the Beaufort scale, so the para At that time [...] there was no scale and so they could be very subjective might want amending. The page is already in the references. 193.62.203.214 15:27, 19 July 2006 (UTC)

[edit] Wind speed formula and deleted section

There was an uncommended deletion of the paragraph that contains the wind speed <> Bft relationship. Since I could not see any reason for this deletion I have re-inserted it. However, the formula is empirical correct (while the factor 0.836 from the German Wikipedia seems to be a slightly better fit) but there is still need for a reference. There is the astonishing fact that the Beaufort number, if interpreted as a result of rounding to the nearest integer, is strongly correlated to the wind speed via a 3/2 power law. This is equivalent to a cubic law for the dynamic pressure of the wind. If the correct coefficient is chosen the formula matches the m/s table with an error of the order of 0.1, the usual decimal precision of the m/s values including those for Beaufort numbers 13 to 16 as tabulated in "Meyers Enzyklopädisches Lexikon" from the mid-seventies ("17" is from above "16" to infinity in that table). So it is clear that this cannot be a random correlation but an intended one. Does anyone know how the Beaufort scale speed values are initially intruduced? Maybe there is an original reference that explicitely uses a power law. If so, then this reference shoud be cited.--SiriusB 13:36, 22 January 2007 (UTC)

This table shows wind speeds for Bft 0-17 (probably equivalent to that in "Meyers Enzyklopädie"). Apparently, also the 0.837 figure yields a good fit to that.--SiriusB 13:53, 22 January 2007 (UTC)

I have checked the goodness of the both fits (0.836 and 0.837) and found that the 0.836 formula is slightly better according to the χ2 criterion (actually, the optimum is near 0.8359). Furthermore, the condition that the Bft wind speed from the formula lies between the maximum speed of a given B number and the minimum speed of the next higher B number is violated only for one number (B=15) for the 0.836 formula but for four numbers for the 0.837 formula. So, the 0.836 formula should be the preferred one (I did not test whether another power law might be better).--SiriusB 14:30, 22 January 2007 (UTC)

Finally, I have found something. The Beaufort scale has indeed been defined by the 0.836 formula, namely after its 1946 (not 1944 according to [5]) revision and extension.

http ://home.att.net/~numericana/answer/scales.htm uses the value 0.8635 for a consistent Beaufort scale. —Preceding unsigned comment added by 91.153.61.242 (talk) 08:39, 2 February 2008 (UTC)
I added the formula probably a few years ago by now. Fitting the 3/2 power law is intentional in development of the formula, although was apparently incidental in the original scale. It was found some decades later to correspond to the 3/2 power law then the scale was refined to better match it. The .837 figure may be explained by lack of robustness at that time which then propagated through the years, although I don't remember the details and haven't run the numbers myself. The source for my figure as I recall was a Terence Meaden paper on the TORRO scale which has its basis in the Beaufort scale. An original source may be preferable, I'll look back at the Meaden paper and its references, and maybe also try a literature search. In the meantime, the (UK) Met Office page uses the converted 1.87*sqrt(B³) figure. Evolauxia (talk) 09:53, 2 February 2008 (UTC)
My understanding is that the Beaufort scale is defined in terms of the state of the sea surface, and not wind speed. That's way I placed the [dubious – discuss] tag. I'll dig around for a reference. Thunderbird2 (talk) 10:50, 2 February 2008 (UTC)
These are relevant:
Thunderbird2 (talk) 10:55, 2 February 2008 (UTC)

[edit] Image

I believe an image near the top of the page makes an article look nicer. I've added a cut version of the force 12 picture (cut: without the text underneath). An anonymous user has deleted it, and I now reinstate it once so we can discuss here whether a picture is appropriate, and if so, whether this is a suitable picture. Classical geographer 20:04, 17 August 2007 (UTC)

Yeah, it's good. Anon edit could well have been vandalism or a test. Debivort 03:00, 18 August 2007 (UTC)

[edit] Beaufort scale in the North Atlantic

For simplicity, why not just peg Beaufort forces 12 through 16 to the Saffir-Simpson hurricane scale? --  Denelson83  01:07, 12 October 2007 (UTC)

[edit] Mean winds?

Does anyone know what 'mean' wind speed is meant? Is it the 10 minute mean that is common now or the one hour mean wind that used to be more common? Subsea (talk) 15:01, 27 February 2008 (UTC)