Beaufort Scale
The story goes that one of our TA (trainers) hates sunny weather - "how can it be good if the beach is full of scangers?" So if one persons good is another persons bad we need to have a way of describing weather that is consistent.
The same problem existed back in the early 1800s when the Royal Navy needed a way of standardising descriptions of weather. The job fell to Irishman Francis Beaufort who designed this scale that developed to become the standard internationally 200 years later.
The scale is normally prefixed with "force" so the terminology is force 1, force 2
Beaufort number |
Wind speed |
Description |
Wave height |
Sea conditions |
Land conditions |
||
km/h |
mph |
|
m |
ft |
|
|
|
0 |
0 |
0 |
Calm |
0 |
0 |
Flat. |
Calm. Smoke rises vertically. |
1 |
1-6 |
1-3 |
Light air |
0.1 |
0.33 |
Ripples without crests. |
Wind motion visible in smoke. |
2 |
7-11 |
4-7 |
Light breeze |
0.2 |
0.66 |
Small wavelets. Crests of glassy appearance, not breaking |
Wind felt on exposed skin. Leaves rustle. |
3 |
12-19 |
8-12 |
Gentle breeze |
0.6 |
2 |
Large wavelets. Crests begin to break; scattered whitecaps |
Leaves and smaller twigs in constant motion. |
4 |
20-29 |
13-18 |
Moderate breeze |
1 |
3.3 |
Small waves. |
Dust and loose paper raised. Small branches begin to move. |
5 |
30-39 |
19-24 |
Fresh breeze |
2 |
6.6 |
Moderate (1.2 m) longer waves. Some foam and spray. |
Smaller trees sway. |
6 |
40-50 |
25-31 |
Strong breeze |
3 |
9.9 |
Large waves with foam crests and some spray. |
Large branches in motion. Whistling heard in overhead wires. |
7 |
51-62 |
32-38 |
Near gale |
4 |
13.1 |
Sea heaps up and foam begins to streak. |
Whole trees in motion. Effort needed to walk against the wind. |
8 |
63-75 |
39-46 |
Gale |
5.5 |
18 |
Moderately high waves with breaking crests forming spindrift. Streaks of foam. |
Twigs broken from trees. Cars veer on road. |
9 |
76-87 |
47-54 |
Strong gale |
7 |
23 |
High waves (2.75 m) with dense foam. Wave crests start to roll over. Considerable spray. |
Light structure damage. |
10 |
88-102 |
55-63 |
Storm |
9 |
29.5 |
Very high waves. The sea surface is white and there is considerable tumbling. Visibility is reduced. |
Trees uprooted. Considerable structural damage. |
11 |
103-119 |
64-73 |
Violent storm |
11.5 |
37.7 |
Exceptionally high waves. |
Widespread structural damage. |
12 |
119 |
73-95 |
Hurricane |
14+ |
46+ |
Huge waves. Air filled with foam and spray. Sea completely white with driving spray. Visibility very greatly reduced. |
Considerable and widespread damage to structures. |
How to end the argument ............
What argument? well put two people on a beach with a bit of wind and they will argue the difference between a 2 & a 3 or whatever. You might find the more experienced tend to have the lower figure - why? Well the beaufort scale was designed for ships under sail at sea so to be technical about it the heights etc are at sea as opposed to on the shore and the wind speed is at a height of 10 metres. Imagine yourself climbing the rigging of an 1800s sail ship - you'll get the idea.
and......
Beaufort notably was the man who is responsible for Charles Darwin traveling on HMS Beagle, a voyage on which he sailed too. This was the expedition that ultimately led to Darwin's book "The origin of the species".
and he had a sea named after him in the Artic - cool or what ?