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I7 Scale

The Beaufort Scale is a system devised in 1805 by Sir Francis Beaufort to describe wind speeds based on observed sea and cloud conditions. It describes 13 levels of winds from calm (sea like a mirror) to hurricane (exceptionally high waves with visibility poor). Wave heights are approximate and can be affected by fetch, depth, swell, rain, tide, and time lag between wind increase and corresponding sea increase.

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Iban Santana Hernandez
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41 views2 pages

I7 Scale

The Beaufort Scale is a system devised in 1805 by Sir Francis Beaufort to describe wind speeds based on observed sea and cloud conditions. It describes 13 levels of winds from calm (sea like a mirror) to hurricane (exceptionally high waves with visibility poor). Wave heights are approximate and can be affected by fetch, depth, swell, rain, tide, and time lag between wind increase and corresponding sea increase.

Uploaded by

Iban Santana Hernandez
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Th e B e a u f o r t S c a l e

This scale of wind speeds devised in 1805 by Sir Francis Beaufort is still in use today. Force 0 1 2 3 4 5 6 7 8 9 10 11 12 Speed knots km/h <1 <1 1-3 1-5 4-6 7-10 11-16 17-21 22-27 6-11 12-19 20-29 30-39 40-50 Conditions Calm, sea like a mirror. Light air, ripples only. Light breeze, small wavelets (0.2m). Crests have a glassy appearance. Gentle breeze, large wavelets (0.6m), crests begin to break. Moderate breeze, small waves (1m), some white horses. Fresh breeze, moderate waves (1.8m), many white horses. Strong breeze, large waves (3m), probably some spray. Near gale, mounting sea (4m) with foam blown in streaks downwind. Gale, moderately high waves (5.5m), crests break into spindrift. Strong gale, high waves (7m), dense foam, visibility affected. Storm, very high waves (9m), heavy sea roll, visibility impaired. Surface generally white. Violent storm, exceptionally high waves (11m), visibility poor. Hurricane, 14m waves, air filled with foam and spray, visibility bad.

28-33 51-61 34-40 62-74 41-47 76-87 8848-55 102 10356-63 118 64+ 119

Wave heights quoted are approximately those that may be expected in the open sea. In enclosed waters the waves will be smaller and steeper. Fetch, depth, swell, heavy rain and tide will also affect their height, and there will also usually be a time lag between any increase in the wind and the consequent increase in the sea.

to devise to make up; to design a breeze a light wind a calm a quiet period light not heavy ripple a very small wave gentle mild a wavelet a not very big wave moderate average a crest the highest part of a wave fresh brisk a white horse a big wave with white crests

a hurricane violent storm appearance the look of violent very strong mounting sea waves increasing visibility how far/well you can see spray small drops of liquid blown through the air impair to reduce affect to influence foam small white bubbles bad not good

a streak thin line poor weak downwind same direction as wind steep goes up or down quickly upwind against the wind fetch waves reflected back spindrift foam or spray blown from the surface of the sea a depth

how deep the sea is a swell the heaving of the sea remaining after a storm generally usually; commonly a time lag the time between; delay exceptionally unusually enclosed waters surrounded by land approximately about to quote to mention

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