Did you know?
The method for measuring wind force was
established in 1806 by an Irishman, Rear Admiral
Sir Francis Beaufort (1774 – 1857). It is called
the Beaufort Scale.
Who was Sir Francis Beaufort?
Born in Navan, Francis Beaufort joined the navy at
the age of 13. He quickly rose through the ranks to
become British Admiralty Hydrographer of the Navy.
This job involved mapping the globe’s oceans and seas.
Apparently Beaufort was shipwrecked as a young boy
because his ship was using incorrect maps. This made
him determined to be incredibly accurate in all his
mapping work. The Beaufort Sea in the Article Circle
is named after Beaufort because of his important
contributions to hydrography.
Beaufort was far from being the archetypal backroom
‘boffin’. Prior to his development of the ‘Beaufort Scale’
of wind measurement, he was severely wounded in the
left arm and chest by sword and blunderbuss during his
time in the Royal Navy when leading a boarding party
to capture a Spanish ship. Later on, during a mapping
expedition in the Mediterranean he was wounded a
second time by a musket ball fired by a band of Turks
that hit him in the groin and damaged his femur.
In 1829, at the age of 55, Beaufort was appointed to run
the Hydrographic Office, which he transformed from a
quiet, dusty backwater, into the greatest collection of
hydrographic data in the World. In 1831, Beaufort wrote
to his friend Commander Fitzroy of the survey ship
HMS Beagle, who was about to return to survey work
off the western shores of Patagonia, recommending ‘A
Mr. Darwin’ - a man ‘full of zeal and enterprise’ - a man
whom, without Beaufort’s recommendation, may never
have changed the foundation of evolutionary biology.
What is the Beaufort Scale?
The Beaufort Scale is based on visual and objective observation of the sea
and how it causes a ship to move. The different categories of sea activity
are described in the chart below. The Beaufort Scale is still used for Met
Eireann’s Sea Area Forecasts.
Force
Appearance of Wind Effects
Wind (Knots) Classification
On the Water
On Land
0
Less than 1
Calm
1
1-3
Light Air
2
4-6
Light Breeze
3
7-10
Gentle
Breeze
4
11-16
Moderate
Breeze
Small waves 1-4 ft. becoming longer,
numerous whitecaps
Dust, leaves, and loose paper lifted,
small tree branches move
5
17-21
Fresh Breeze
Moderate waves 4-8 ft taking longer
form, many whitecaps, some spray
Small trees in leaf begin to sway
6
22-27
Strong
Breeze
Larger waves 8-13 ft, whitecaps
common, more spray
Larger tree branches moving,
whistling in wires
7
28-33
Near Gale
Sea heaps up, waves 13-19 ft, white
foam streaks off breakers
Whole trees moving, resistance felt
walking against wind
Gale
Moderately high (18-25 ft) waves of
greater length, edges of crests begin
to break into spindrift, foam blown in
streaks
Twigs breaking off trees, generally
impedes progress
8
34-40
9
41-47
10
11
12
Sea surface smooth and mirror-like
Calm, smoke rises vertically
Scaly ripples, no foam crests
Smoke drift indicates wind direction,
still wind vanes
Small wavelets, crests glassy, no
breaking
Wind felt on face, leaves rustle, vanes
begin to move
Large wavelets, crests begin to break, Leaves and small twigs constantly
scattered whitecaps
moving, light flags extended
High waves (23-32 ft), sea begins
Strong Gale to roll, dense streaks of foam, spray
may reduce visibility
48-55
Storm
Very high waves (29-41 ft) with
overhanging crests, sea white with
densely blown foam, heavy rolling,
lowered visibility
56-63
Violent
Storm
Exceptionally high (37-52 ft) waves,
foam patches cover sea, visibility
more reduced
Hurricane
Air filled with foam, waves over 45
ft, sea completely white with driving
spray, visibility greatly reduced
64+
Slight structural damage occurs, slate
blows off roofs
Seldom experienced on land, trees
broken or uprooted, “considerable
structural damage”
(Source, public domain: Royal Museums Greenwich)
Activity
•
Go to http://www.independent.ie/irish-news/education/kilcullen-voyagers/ and
watch the Kilkullen Yoyager Sunrise Sailing video.
•
Look at how the sea changes in the video.
•
Use the descriptions in the chart to guess the Beaufort Wind Scale throughout
the video.
•
When you’re next outside, use the chart to measure the Beaufort Wind Scale on
land. Look at the movement of leaves on the trees or think about the strength of
the wind in your hair to help you guess the Beaufort Wind Scale.