The Beaufort scale is an empirical measure for the intensity of the wind based mainly on sea-state or wave conditions. Its full name is the Beaufort wind force scale. It should be noted that the wave heights given pertain to the conditions found at open sea.

The scale was created by the Irish naval commander Sir Francis Beaufort around 1805. The initial scale did not have wind speeds, but listed a set of qualitative conditions from 0 to 12 by how a naval vessel would act under them - from 'just sufficient to give steerage' to 'that which no canvas could withstand'. The scale was made a standard part of log entries for Royal Navy vessels in the late 1830s. A knot is a non SI unit of speed equal to one nautical mile per hour. ... Kilometre per hour (American spelling: kilometer per hour) is a unit of both speed (scalar) and velocity (vector). ... Miles per hour is a unit of speed, expressing the number of international miles covered per hour. ... A knot is a non SI unit of speed equal to one nautical mile per hour. ... Kilometre per hour (American spelling: kilometer per hour) is a unit of both speed (scalar) and velocity (vector). ... Miles per hour is a unit of speed, expressing the number of international miles covered per hour. ... A wave crashing against the shore A wave is a disturbance that propagates. ... Sir Francis Beaufort (1774 - 1856) was a great Irish hydrographer (map-maker). ... 1805 was a common year starting on Tuesday (see link for calendar). ... Events and Trends Electromagnetic induction discovered by Michael Faraday Dutch-speaking farmers known as Voortrekkers emigrate northwards from the Cape Colony Croquet invented in Ireland Railroad construction begins in earnest in the United States Egba refugees fleeing the Yoruba civil wars found the city of Abeokuta in south-west Nigeria...

The scale was adapted to non-naval use from the 1850s, with the Beaufort numbers being tied to cup anemometer rotations. The rotations to number was standardised only in 1923 and the measure was slightly altered some decades later to improve its utility for meteorologists. Today, hurricanes are sometimes numbered 12 through 16 using the Saffir-Simpson Hurricane Scale, with a Category 1 hurricane bearing Beaufort number 12, a Category 2 hurricane, Beaufort 13, and so on. Anemometer installation on roof of Deconism Gallery, using three size 6, schedule 40 pipes in their original uncut 20 foot (6 m) lengths. ... 1923 was a common year starting on Monday (link will take you to calendar). ... The Saffir-Simpson Hurricane Scale is a scale classifying hurricanes by the intensity of their sustained winds, developed in 1969 by civil engineer Herbert Saffir and National Hurricane Center director Bob Simpson. ...

The scale is used in, and may be most recognisable to some from, the Shipping Forecasts broadcast on BBC Radio 4 in the United Kingdom. The Shipping Forecast is a regular feature of BBC Radio 4 and is provided by the UK Meteorological Office. ... BBC Radio 4 is a British domestic radio station which broadcasts a wide variety of chiefly spoken-word programmes including news, drama, comedy, science and history. ...

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"), and anything stronger a hurricane warning. A small craft advisory is a type of warning issued by the National Weather Service in the United States, most frequently in coastal areas. ... It has been suggested that this article or section be merged with Severe weather terminology. ... 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 of Tropical Storm or Hurricane intensity. ...

External links

• UK Meteorological Office: The Beaufort Scale
• Investigating Clouds : A lesson plan from the National Science Digital Library that uses the Beaufort Scale.
• US National Weather Service description of Beaufort Scale : Includes photos of accompanying sea appearance.

Bibliography

Scott Huler, Defining the Wind : The Beaufort Scale, and How a 19th-Century Admiral Turned Science into Poetry, Crown, 2004, ISBN: 1400048842