Date: Fri, 27 Oct 1995 03:07:51 -1000 From: andrew@tug.com (Andrew Beattie) Message-Id: Organization: /usr/lib/news/organisation Subject: Re: Beauforts salanne@convex.csc.FI (Simo Salanne) writes: >Beaufort scale is >nonlinear, it is unmeasurable: it's _defined_ to be based on >observations (like the movement of leaves in a tree). Is this true? The Beaufort scale is certainly often described using such observations, but is it truly *defined* this way? It is certainly reasonable for a property which has non-linear effects to be measured on a non-linear scale. I have long harboured the *hope* that beneath the table of values presented, there is in fact a logarithmic or other simple non-linear relationship lurking upon which the scale was based. I would presume that Beaufort produced a paper when he first proposed his scale. Is there anyone here who has access to this that can provide us an authoritive reference? For those that would like to study the figures, here is a table that I've snarfled from SKII (thanks Nop) Beaufort m/s km/h mph knots 1 0-2 0-7 0-4 0-4 2 2-3 7-11 4-7 4-6 3 3-5 11-20 7-13 6-11 4 5-8 20-28 13-18 11-16 5 8-11 28-38 18-24 16-21 6 11-14 38-50 24-31 21-28 7 14-17 50-61 31-38 28-34 8 17-20 61-72 38-45 34-40 9 20-24 72-86 45-54 40-48 Hmmm... maybe it would be useful to make a conversion table: -TO-> |meters |kms |miles |knots |feet |attoparsecs | | *multiply* |per |per |per | |per |per | v FROM |second |hour |hour | |second |microfortnight | ---------------+-------+-------+-------+-------+-------+---------------| meters | | | | | | | per |1.00000|3.60000|2.23697|1.94384|3.28084|39.20047 | second | | | | | | | ---------------+-------+-------+-------+-------+-------+---------------| kms | | | | | | | per |0.27778|1.00000|0.62137|0.53996|0.91134|10.88902 | hour | | | | | | | ---------------+-------+-------+-------+-------+-------+---------------| miles | | | | | | | per |0.44704|1.60934|1.00000|0.86898|1.46667|17.52418 | hour | | | | | | | ---------------+-------+-------+-------+-------+-------+---------------| knots | | | | | | | |0.51444|1.85200|1.15078|1.00000|1.68781|20.1664 | | | | | | | | ---------------+-------+-------+-------+-------+-------+---------------| feet | | | | | | | per |0.30480|1.09728|0.68182|0.59248|1.00000|0.1194830 | second | | | | | | | ---------------+-------+-------+-------+-------+-------+---------------| attoparsecs | | | | | | | per |0.02552|0.09184|0.09184|0.04959|0.08369|1.00000000 | microfortnight | | | | | | | ---------------+-------+-------+-------+-------+-------+---------------+ Look up what yo want to converr *from* on the left of the table. Look up what you want to convert *to* on the top of the table. Convert by multiplying by the number at the intersection. Andrew -- New to rec.kites? START HERE! | To: www@kfs.org send an email message like this-> | Subject: service /-\ () >< () |\/| () >< () /-\ | http://www.kfs.org/kites/welcome Psst! Wanna buy a roll of white, wide, Carrington seconds? gimme a call! = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Date: Sat, 28 Oct 1995 01:09:50 -1000 From: salanne@convex.csc.FI (Simo Salanne) Message-Id: <46t31u$s4c@pobox.csc.fi> Organization: STACK Finland Subject: Re: Beauforts In andrew@tug.com (Andrew Beattie) writes: > > salanne@convex.csc.FI (Simo Salanne) writes: > >Beaufort scale is > >nonlinear, it is unmeasurable: it's _defined_ to be based on > >observations (like the movement of leaves in a tree). > > Is this true? The Beaufort scale is certainly often described using > such observations, but is it truly *defined* this way? > The following "definition" is from C.A. Marchaj, Sailing Theory and Practice, Allard Coles Ltd, 1964, page 434. Beaufort Description of sea 0 Sea like a mirror 1 Ripples, no foam crests 2 Small wavelets, crests have a glassy appearance and do not break 3 Large wavelets, crests begin to break. Perhaps scattered white caps 4 Small waves becoming longer. Fairly frequent white caps. 5 Moderate waves, taking a more pronounced longe form. Many white caps, some spray. 6 Large waves begin to form. Extensive white caps everywhere, some spray. 7 Sea heaps up and white foam from breaking waves begins to be blown in well-marked streaks along the direction of the wind. 8 Moderately high waves of greater lenght. Edges of crests break into spindrift. The foam is blown in well-marked streaks along the direction of the wind. 9 High waves. Dense streaks of foam along the direction of the wind. Spray may affect visibility. Sea begins to roll. 10 Very high waves with long overhanging crests. The surface of the sea takes on a white appearnace. The rolling of the sea becomes heavy and shocklike. Visibility is affected. 11 Exceptionally high waves. The sea is completely covered with long white patches of foam. Visibility is affected. Small- and medium-sized ships are lost to view for long periods. 12 The air is filled with foam and spray. Sea completely white with driving spray. Visibility seriously affected. In the text Marchaj writes: "The size of waves cannot be estimated solely on the basis of the wind speed, and the description of waves in the Beaufort scale is rather misleading. It is, for instance, well known that storm waves in the North Atlantic can reach a height of 35 feet, with a lenght of 1000 ft., while those in the Baltic seldom exceed 8 ft. in height and 100 ft. in lenght. THE BEAUFORT SCALE IS DESCRIBING THE BEHAVIOUR OF THE SEA - NOT THE BAHAVIOUR OF THE WIND. (The early version of the scale described the behaviour of a battle ship.?) It's very absurd to use Beaufort scale on land, where kites - mostly - are flown. Smooth Winds in m/s Simo P.S. There's a "Psychological Scale" from Yachting Magazine, U.S.A. 1 Boredom 2 Mild pleasure 3 Pleasure 4 Great pleasure 5 Delight 6 Delight tinged with anxiety 7 Anxiety tinged with fear 8 Fear tinged with terror 9 Great terror 10 Panic 11 I want my mummy 12 Yes, Mr. Jones -- Simo.Salanne@csc.fi STACK Finland & STARRC Chair ==================================================================== http://www.kfs.org/kites/simo/simo.html = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =