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Land Beaufort ScaleThe Beaufort Scale was originally developed in 1805 by Sir Francis Beaufort as a system for estimating wind strengths without the use of instruments. It is currently still in use for this same purpose as well as to tie together various components of weather (wind strength, sea state, observable effects) into a unified picture. |
| Force | Speed | Land Conditions | |
|---|---|---|---|
| knots | mph | ||
| 0 | <1 | <1 | Calm, smoke rises vertically |
| 1 | 1-3 | 1-3 | Light air, direction of wind shown by smoke drift only |
| 2 | 4-6 | 4-7 | Light breeze, wind felt on face, leaves rustle, vanes moved by wind |
| 3 | 7-10 | 8-12 | Gentle breeze, leaves and small twigs in constant motion, wind extends light flag |
| 4 | 11-16 | 13-18 | Moderate breeze, raises dust, loose paper, small branches move |
| 5 | 17-21 | 19-24 | Fresh breeze, small trees in leaf begin to sway |
| 6 | 22-27 | 25-31 | Strong breeze, large branches in motion, umbrellas used with difficulty |
| 7 | 28-33 | 32-38 | Near gale, whole trees in motion, inconvenience felt walking against the wind |
| 8 | 34-40 | 39-46 | Gale, breaks twigs off trees, impedes progress |
| 9 | 41-47 | 47-54 | Strong gale, slight structural damage occurs |
| 10 | 48-55 | 55-63 | Storm, trees uprooted, considerable damage occurs |
| 11 | 56-63 | 64-73 | Violent storm, widespread damage |
| 12 | 64+ | 74+ | Hurricane, extreme destruction |
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http://www.ncdc.noaa.gov/ol/climate/conversion/beaufortland.html Last updated 25 May 2000 by ncdc.webmaster@noaa.gov Please see the NCDC Contact Page if you have questions or comments. |