|
|
|
Home & Information
Technical Support
ADB Products
Related Products |
Technical Reference 
Navigation:
HOME |
technical reference overview
> miscellaneous
> miscellany
> Beaufort scale
|
The Beaufort Scale - Wind Speeds
One of the first scales to estimate wind speeds and the effects was created by Britain's Admiral Sir Francis Beaufort (1774-1857). He developed the scale in 1805 to help sailors estimate the winds via visual observations.
The scale starts with 0 and goes to a force of 12. The Beaufort scale is still used today to estimate wind strengths.
An approximate description is given for each force (for use on land). It should be noted that wind speed is generally 30% stronger 10m above ground level.
 |
The Beaufort Scale | |||||
| Scale | MPH¹ | Knots¹ | Sea Height² | Description | Specifications | |
|---|---|---|---|---|---|---|
| 0 | <1 | <1 | - | Calm | Calm; smoke rises vertically. | |
| 1 | 1 - 3 | 1 - 3 | ¼ | Light air | Direction of wind shown by smoke drift, but not by wind vanes. | |
| 2 | 4 - 7 | 4 - 6 | ½ | Light breeze | Wind felt on face; leaves rustle; ordinary vanes moved by wind. | |
| 3 | 8 - 12 | 7 - 10 | 2 | Gentle breeze | Leaves and small twigs in constant motion; wind extends light flag. | |
| 4 | 13 - 18 | 11 - 16 | 3½ | Moderate breeze | Raises dust and loose paper; small branches are moved. | |
| 5 | 19 - 24 | 17 - 21 | 6 | Fresh breeze | Small trees in leaf begin to sway; crested wavelets form on inland waters. | |
| 6 | 25 - 31 | 22 - 27 | 9½ | Strong breeze | Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty. | |
| 7 | 32 - 38 | 28 - 33 | 13½ | Near gale | Whole trees in motion; inconvenience felt when walking against the wind. | |
| 8 | 39 - 46 | 34 - 40 | 18 | Gale | Breaks twigs off trees; generally impedes progress. | |
| 9 | 47 - 54 | 41 - 47 | 23 | Strong gale | Slight structural damage occurs (chimney-pots and slates removed). | |
| 10 | 55 - 63 | 48 - 55 | 29 | Storm | Seldom experienced inland; trees uprooted; considerable structural damage occurs. | |
| 11 | 64 - 72 | 56 - 63 | 37 | Violent strom | Very rarely experienced; accompanied by wide-spread damage. | |
| 12 | >73 | >64 | - | Hurricane | ||
² Sea height is measured in feet
See also:
|
 |
 |