The Beaufort scale (pronounced /ˈboʊfət/) is an empirical measure for describing wind speed based mainly on observed sea conditions. A central concept in Science and the Scientific method is that all Evidence must be empirical, or empirically based that is dependent on evidence Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) Wind speed is the Speed of Wind, the movement of air or other gases in an atmosphere Its full name is the Beaufort wind force scale.

Contents 1 History 2 The modern scale 3 References 4 See also 5 External links

History

The scale was created in 1805 by Sir Francis Beaufort, an Irish-British admiral and hydrographer. Year 1805 ( MDCCCV) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or Rear-Admiral Sir Francis Beaufort, FRS, FRGS (7 May 1774 &ndash 17 December 1857 was a Hydrographer and officer in Britain 's Royal Navy Ireland (pronounced /ˈaɾlənd/ Éire) is the third largest island in Europe, and the twentieth-largest island in the world The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located Hydrography focuses on the measurement of physical characteristics of Waters and marginal land The scale that carries Beaufort's name had a long and complex evolution, from the previous work of others, to when Beaufort was a top administrator in the Royal Navy in the 1830s. In the early 19th Century naval officers made regular weather observations, but there was no standard scale and so they could be very subjective - one man's "stiff breeze" might be another's "soft breeze". Beaufort succeeded in getting things standardized.

The initial scale of thirteen classes (zero to twelve) did not reference wind speed numbers, but related qualitative wind conditions to effects on the sails of a man of war, then the main ship of the Royal Navy, from "just sufficient to give steerage" to "that which no canvas sails could withstand. Wind speed is the Speed of Wind, the movement of air or other gases in an atmosphere A man-of-war (also man of war, man-o'-war or simply man) is an armed naval vessel The Royal Navy of the United Kingdom is the oldest of the British armed services (and is therefore known as the Senior Service) A sail is any type of surface intended to generate Thrust by being placed in a Wind &mdashin essence a vertically-oriented Wing. " At zero, all his sails would be up; at six, half of his sails would have been taken down; and at twelve, all sails would be stowed away. ^[1]

The scale was made a standard for ship's log entries on Royal Navy vessels in the late 1830s, and was adapted to non-naval use from the 1850s, with scale numbers corresponding to cup anemometer rotations. An anemometer is a device for measuring wind speed and is one instrument used in a Weather station. In 1906, to accommodate the growth of steam power, the descriptions were changed to how the sea, not the sails, behaved and extended to land observations. Rotations to scale numbers were standardized only in 1923. George Simpson, Director of the UK Meteorological Office, was responsible for this and for the addition of the land-based descriptors. Sir George Clarke Simpson KCB CBE FRS (1878–1965 was a British meteorologist, born in Derby, England. For the UKMET model see Tropical cyclone forecast model. The Met Office (originally an abbreviation for Meteorological Office, ^[2] The measure was slightly altered some decades later to improve its utility for meteorologists. Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary Today, many countries have abandoned the scale and use the SI-based units m/s or km/h instead, but the severe weather warnings given to public are still approximately the same as when using the Beaufort scale. Severe weather is any destructive weather phenomenon. The term is usually used to refer to severe thunderstorms and related phenomena such as Tornados

The Beaufort scale was extended in 1946, when Forces 13 to 17 were added. However, Forces 13 to 17 were intended to apply only to special cases, such as tropical cyclones. Nowadays, the extended scale is only used in Taiwan and mainland China, which are often affected by typhoons.

Wind speed on the 1946 Beaufort scale is based on the empirical formula:^[3]

v = 0. 836 B^3/2 m/s

where v is the equivalent wind speed at 10 metres above the surface and B is Beaufort scale number. For example, B = 9. 5 is related to 24. 5 m/s which is equal to the lower limit of "10 Beaufort". Using this formula the highest winds in hurricanes would be 23 in the scale.

Today, hurricanes are sometimes described as Beaufort scale 12 through 16, very roughly related to the standard Saffir-Simpson Hurricane Scale where Category 1 is equivalent to Beaufort 12. A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding The Saffir-Simpson Hurricane Scale is a classification used for most Western Hemisphere Tropical cyclones that exceed the intensities of Tropical depressions However, the Saffir-Simpson Scale does not match the extended Beaufort numbers above 13. Category 1 tornadoes on the Fujita and TORRO scales also begin roughly at the end of level 12 of the Beaufort scale but are indeed independent scales. A tornado is a violent rotating column of air which is in contact with both the surface of the earth and a Cumulonimbus cloud or in rare cases the base of a Cumulus The Fujita scale ( F-Scale) or Fujita-Pearson scale, is a scale for rating Tornado intensity based on the damage tornadoes inflict on human-built structures The TORRO tornado intensity scale (or T-Scale) is a scale measuring Tornado intensity between T0 and T11

Note that wave heights in the scale are for conditions in the open ocean, not along shore. An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere.

The modern scale

Beaufort number	Wind speed				Mean wind speed (kn / km/h / mph)	Description	Wave height		Sea conditions	Land conditions	Sea state photo
	kn	km/h	mph	m/s			m	ft
0	0	0	0	0-0. (For the South African airport with IATA code "KMH" see Johan Pienaar Airport. The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International A foot (plural feet or foot; symbol or abbreviation ft or sometimes &prime – the prime symbol) is a non-SI unit 2	0 / 0 / 0	Calm	0	0	Flat. Calm is an Adjective meaning peaceful quiet particularly used of the weather free from wind or Storm, or of the sea as opposed to rough	Calm. Smoke rises vertically.
1	1-3	1-6	1-3	0. 3-1. 5	2 / 4 / 2	Light air	0. 1	0. 33	Ripples without crests.	Wind motion visible in smoke.
2	4-6	7-11	4-7	1. 6-3. 3	5 / 9 / 6	Light breeze	0. 2	0. 66	Small wavelets. Crests of glassy appearance, not breaking	Wind felt on exposed skin. Leaves rustle.
3	7-10	12-19	8-12	3. 4-5. 4	9 / 17 / 11	Gentle breeze	0. 6	2	Large wavelets. Crests begin to break; scattered whitecaps	Leaves and smaller twigs in constant motion.
4	11-15	20-29	13-18	5. 5-7. 9	13 / 24 / 15	Moderate breeze	1	3. 3	Small waves.	Dust and loose paper raised. Small branches begin to move.
5	16-21	30-39	19-24	8. 0-10. 7	19 / 35 / 22	Fresh breeze	2	6. 6	Moderate (1. 2 m) longer waves. Some foam and spray.	Smaller trees sway.
6	22-27	40-50	25-31	10. 8-13. 8	24 / 44 / 27	Strong breeze	3	9. 9	Large waves with foam crests and some spray.	Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult.
7	28-33	51-62	32-38	13. 9-17. 1	30 / 56 / 35	Near Gale/Moderate gale	4	13. A gale is a very strong Wind. There are conflicting definitions of how strong 1	Sea heaps up and foam begins to streak.	Whole trees in motion. Effort needed to walk against the wind.
8	34-40	63-75	39-46	17. 2-20. 7	37 / 68 / 42	Fresh Gale	5. A gale is a very strong Wind. There are conflicting definitions of how strong 5	18	Moderately high waves with breaking crests forming spindrift. Streaks of foam.	Twigs broken from trees. Cars veer on road.
9	41-47	76-87	47-54	20. 8-24. 4	44 / 81 / 50	Strong Gale	7	23	High waves (6-7 m) with dense foam. A gale is a very strong Wind. There are conflicting definitions of how strong Wave crests start to roll over. Considerable spray.	Light structure damage.
10	48-55	88-102	55-63	24. 5-28. 4	52 / 96 / 60	Whole Gale/Storm	9	29. A gale is a very strong Wind. There are conflicting definitions of how strong A storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface and strongly implying Severe weather. 5	Very high waves. The sea surface is white and there is considerable tumbling. Visibility is reduced.	Trees uprooted. Considerable structural damage.
11	56-63	103-119	64-73	28. 5-32. 6	60 / 112 / 70	Violent storm	11. 5	37. 7	Exceptionally high waves.	Widespread structural damage.
12	64-80	120	74-95	32. 7-40. 8	73 / 148 / 90	Hurricane	14+	46+	Huge waves. A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding Air filled with foam and spray. Sea completely white with driving spray. Visibility greatly reduced.	Considerable and widespread damage to structures.

The scale is used in, and may be most recognizable to some from, the Shipping Forecasts broadcast on BBC Radio 4 in the United Kingdom. The Shipping Forecast is a four-times-daily BBC radio broadcast of Weather reports and forecasts for the seas around the coasts of the British Isles. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located

This scale is also widely used in China, Taiwan, Hong Kong and Macau, however with some differences between them. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National Taiwan ( Taiwanese: Tâi-oân/Tāi-oân (historically 大灣/台員/大員/台圓/大圓/台窩灣 is an Island in East Asia. Hong Kong ( officially the Hong Kong Special Administrative Region, is a territory located on China 's south coast on the Pearl River Delta, and borders For a topic outline on this subject see List of basic Macau topics. Taiwan uses the Beaufort scale with the extension to 17 noted above. Taiwan ( Taiwanese: Tâi-oân/Tāi-oân (historically 大灣/台員/大員/台圓/大圓/台窩灣 is an Island in East Asia. China also switched to this extended version without prior notice on the morning of May 15, 2006^[4], and the extended scale was immediately put to use for Typhoon Chanchu. Typhoon Chanchu (international designation 0601, JTWC designation 02W, also designated Typhoon Caloy by PAGASA, and sometimes Hong Kong and Macau however keep using Force 12 as the maximum. Hong Kong ( officially the Hong Kong Special Administrative Region, is a territory located on China 's south coast on the Pearl River Delta, and borders For a topic outline on this subject see List of basic Macau topics.

In the United States, winds of Beaufort 6 or 7 result in the issuance of a small craft advisory, with force 8 or 9 winds bringing about a gale warning, 10 or 11 a storm warning (or "tropical storm warning" for 8 to 11 if related to a tropical cyclone), and anything to 12 a hurricane warning. The United States of America —commonly referred to as the A small craft advisory is a type of warning issued by the National Weather Service in the United States, most frequently in coastal areas A gale warning is an advisory or warning issued by the local competent authority in maritime countries about the existence of winds of gale force or above or the imminent occurrence A storm warning generally refers to an advisory issued by an official meteorological department to warn citizens of approaching dangerous Weather. Warnings and watches are two levels of alert issued by national Weather forecasting bodies to coastal areas threatened by the imminent approach of a Tropical cyclone A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding Warnings and watches are two levels of alert issued by national Weather forecasting bodies to coastal areas threatened by the imminent approach of a Tropical cyclone

References

• Huler, Scott (2004). Defining the Wind: The Beaufort Scale, and How a 19th-Century Admiral Turned Science into Poetry. Crown. ISBN 1-4000-4884-2.  

• Force Ten, Rush

See also

• American Practical Navigator
• Saffir-Simpson Hurricane Scale
• Douglas Sea Scale
• Enhanced Fujita Scale
• Fujita scale
• TORRO scale
• Cliwoc
• Sea state

External links

• UK Meteorological Office: The Beaufort Scale
• Investigating Clouds, a lesson plan from the National Science Digital Library that uses the Beaufort Scale. History The most popular navigational text of the late 18th centurywas The New Practical Navigator by John Hamilton Moore. The Saffir-Simpson Hurricane Scale is a classification used for most Western Hemisphere Tropical cyclones that exceed the intensities of Tropical depressions The Douglas Sea Scale is a scale which measures the height of the waves and also measures the swell of the sea The Enhanced Fujita Scale, or EF Scale, is the scale for rating the strength of Tornadoes in the United States estimated via the damage they cause The Fujita scale ( F-Scale) or Fujita-Pearson scale, is a scale for rating Tornado intensity based on the damage tornadoes inflict on human-built structures The TORRO tornado intensity scale (or T-Scale) is a scale measuring Tornado intensity between T0 and T11 The Climatological database for the world's oceans (CLIWOC was a research project to convert ships' logbooks into a computerised database A sea state includes the height, Period, and character of waves on the surface of a large body of water
• Radio interview with Scott Huler.
• OceanWeather.com gives current graphics for wind, waves and temperature
• Open Source Textbook at Oceanworld.tamu.edu cites the original definition formula in chapter 4
• Howtoon Poster showing effects on land/sea effects at each step.

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