The beaufort scale is a scale that relates to wind speed and is useful for giving a rough wind speed when no equipment is available. The scale was devised in 1805 by a Royal Navy officer, Francis Beaufort. Beaufort saw it as a way to standardise the wind speed scale, the main reason for it was because one sailor's strong breeze could be considered light by others which made reporting wind observations difficult.
The modern Beaufort scale has 13 different stages, ranging from 0 where wind is less than 1km/h to 13 where winds are over 118km/h. The table below explains what observations can be made to determine the current beaufort rating.
|Beaufort Number||Description||Wind Speed (km/h)||Observations|
|0||Calm||<1||Calm. Smoke rises vertically.|
|1||Light Air||1.1 - 5.5||Smoke drift indicates wind direction and wind vanes cease moving.|
|2||Light Breeze||5.6 - 11||Wind felt on exposed skin. Leaves rustle and wind vanes begin to move.|
|3||Gentle Breeze||11 - 19||Leaves and small twigs constantly moving, light flags extended.|
|4||Moderate Breeze||19 - 28||Dust and loose paper raised. Small branches begin to move.|
|5||Fresh Breeze||28 - 38||Branches of a moderate size move. Small trees in leaf begin to sway.|
|6||Strong Breeze||38 - 49||Large branches in motion. Whistling heard in overhead wires. Umbrella use becomes difficult.|
|7||High Wind||49 - 61||Whole trees in motion. Effort needed to walk against the wind.|
|8||Gale||61 - 74||Some twigs broken from trees. Progress on foot is seriously impeded.|
|9||Strong Gale||74 - 88||Some branches break off trees, and some small trees blow over.|
|10||Storm||88 - 102||Trees are broken off or uprooted, saplings bent and deformed.|
|11||Violent Storm||102 - 117||Widespread damage to vegetation. Many roofing surfaces are damaged|
|12||Hurricane Force||>117||Very widespread damage to vegetation. Some windows may break. Debris may be hurled about.|