Measure Wind Speed Using
the Beaufort Scale
Wind speed is measured by using a scale of 0-12 based on what you can see happening around you. It was originally developed in 1806 by Sir Francis Beaufort. In the TV weather forecasters usually use kilometers per hour to describe wind speed or they use the words in the column on the right, when sailing, the Beaufort Force scale is still used!
|
Beaufort
Force
|
Wind Speed
(KmPH)
|
Wind Speed
(MPH)
|
Clues
|
Terms Used in Forecasts
|
|
0
|
0-2
|
0-1
|
Calm;
smoke rises straight up from chimneys.
|
Calm
|
|
1
|
2-5
|
1-3
|
Shown by
direction of wind smoke drift, but not by wind vanes as it isn’t strong
enough to make them move.
|
Light
|
|
2
|
6-12
|
4-7
|
Wind felt
on face, leaves rustle; ordinary vanes moved by wind.
|
Light
|
|
3
|
13-20
|
8-12
|
Leaves
and small twigs in constant motion; wind extends light flag.
|
Gentle
|
|
4
|
21-29
|
13-18
|
Raises
dust and loose paper; small branches are moved.
|
Moderate
|
|
5
|
30-39
|
19-24
|
Small
trees with leaves on begin to sway
|
Fresh
|
|
6
|
40-50
|
25-31
|
Large
branches in motion; umbrellas used with difficulty.
|
Strong
|
|
7
|
51-61
|
32-38
|
Whole
trees in motion; it’s difficult to walk against the wind.
|
Strong
|
|
8
|
62-74
|
39-46
|
Breaks
twigs off trees; more difficult to walk
|
Gale
|
|
9
|
75-87
|
47-54
|
Slight
damage to buildings, loose tiles may fall off roofs
|
Gale
|
|
10
|
88-101
|
55-63
|
Trees uprooted;
lots of damage to buildings
|
Whole gale
|
|
11
|
102-116
|
64-72
|
Widespread
damage, light building collapse
|
Whole gale
|
|
12
|
117 or more
|
73 or more
|
Houses
and other buildings collapse.
|
Hurricane
|
To use this table go outside and look at the trees; are the leaves, twigs or branches moving? Look at any smoke you can see from chimneys; is it rising straight into the air? Can you feel the wind on your face? You can then use this table to help you decide on the wind speed and record it on your weather record sheet.