| Force |
Wind
Knots |
Description |
Estimating Wind
Speed |
| Effects At Sea |
Effects Near Land |
Effects On Land |
| 0 |
Under 1 |
Calm |
Sea like a mirror |
Calm |
Calm; smoke rises vertically |
| 1 |
1-3 |
Light Air |
Ripples with appearance of scales; no foam
crests |
Small sailboat just has steerage way |
Smoke drift indicates wind direction; vanes
do not move |
| 2 |
4-6 |
Light Breeze |
Small wavelets; crests of glassy appearance;
not breaking |
Wind fills the sails of small boats which
then travel at about 1-2 knots |
Wind felt on face; leaves rustle; vanes begin
to move |
| 3 |
7-10 |
Gentle Breeze |
Large wavelets; crests begin to break,
scattered whitecaps |
Sailboats begin to heel and travel at about
3-4 knots |
Leaves and small twigs in constant motion;
light flags extended |
| 4 |
11-16 |
Moderate Breeze |
Small waves 1-4 ft., becoming longer;
numerous whitecaps |
Good working breeze, sailboats carry all sail
with good heel |
Dust, leaves, and loose paper raised up;
small branches move. |
| 5 |
17-21 |
Fresh Breeze |
Moderate waves 4-8 ft taking longer form;
many whitecaps; some spray |
Sailboats shorten sail |
Small trees in leaf begin to sway |
| 6 |
22-27 |
Strong Breeze |
Larger waves 8-13 ft forming white caps
everywhere; more spray |
Sailboats have double reefed mainsails |
Larger branches of trees in motion; whistling
heard in wires |
| 7 |
28-33 |
Near Gale |
Sea heaps up, waves 13-20 ft; white foam from
breaking waves begins to be blon in streaks |
Boats remain in harbor; those at sea heave-to |
Whole trees in motion; resistance felt in
walking against wind |
| 8 |
34-40 |
Gale |
Moderately high (13-20 ft) waves of greater
length; edges of crests begin to break into
spindrift; foam is blown in wellmarked streaks |
Boats remain in harbor; those at sea heave-to |
Whole trees in motion; resistance felt
inwalking against wind |
| 9 |
41-47 |
Strong Gale |
High waves (20 ft); sea begins to roll; dense
streaks of foam; spray may reduce visibility |
|
Slight structural damage occure; slate blows
from roofs |
| 10 |
48-55 |
Storm |
Very high waves (20-30 ft) with overhanging
crests;sea takes a white apperance as foam is
blown in very dense streaks; rolling is heavy and
visibility is reduced |
|
Seldom experienced on land; trees broken or
uprooted; considerable structural damage occurs |
| 11 |
56-63 |
Violent Storm |
Exceptionally high (30-45 ft) waves; sea
covered with white foam patches; visibility still
more reduced |
|
|
| 12 |
64 -up |
Hurricane |
Air filled with foam; waves over 45 ft; sea
completely white with driving spray; visibility
greatly reduced |
|
|
Note: The Beaufort Wind Scale goes to Force 12. It is
only academic at this level. All sailors by this time are
in port, wish they were, being beaten up, or sinking.
