Beaufort Wind Speed Scale
BEAUFORT WIND SPEED SCALE
|
Beaufort
Force
Number
|
Wind Speed
in:
|
Term
|
Indications on
Land and Sea
|
| km/hr | knots |
| 0 | calm | calm | Calm | Land: Smoke rises vertically.
Sea: Sea like mirror. |
| 1 | 2-5 | 1-3 | Light Air | Land: Smoke drifts slowly downwind.
Sea: Ripples with appearance of scales:
no foam crests. |
| 2 | 6-11 | 4-6 | Light Breeze | Land: Leaves rustle.
Sea: Small wavelets;
crests of glassy appearance, not breaking. |
| 3 | 12-18 | 7-10 | Gentle Breeze | Land: Leaves are
in motion.
Sea: Large wavelets;
crests begin to break; scattered whitecaps. |
| 4 | 19-30 | 11-16 | Moderate Breeze | Land: Small branches
on trees move.
Sea: Small waves, becoming longer;
numerous whitecaps. |
| 5 | 31-39 | 17-21 | Fresh Breeze | Land: Small trees sway. Sea: Moderate waves, taking longer form;
many whitecaps;
some spray. |
| 6 | 40-50 | 22-27 | Strong Breeze | Land: Large
branches sway.
Sea: Larger waves forming; whitecaps
everywhere; more spray. |
| 7 | 51-61 | 28-33 | Near Gale | Land: Whole trees
in motion.
Sea: Sea heaps up;
white foam from breaking waves begins to be blown in streaks. |
| 8 | 62-74 | 34-40 | Gale | Land: Twigs and small branches break off trees.
Sea: Moderately high waves of greater length; edges of crests begin to break into spindrift; foam is blown in well-marked streaks. |
| 9 | 75-87 | 41-47 | Strong Gale | Land: Large branches break off trees;
slight structural damage.
Sea: High waves; sea begins to roll; dense
streaks of foam; spray may reduce visibility. |
| 10 | 88-102 | 48-55 | Storm | Land: Trees broken; minor structural damage.
Sea: Very high waves with overhanging crests; sea takes white appearance as foam is blown in very dense streaks; rolling is heavy and visibility is reduced. |
| 11 | 103-117 | 56-63 | Violent Storm | Land: Widespread damage.
Sea: Exceptionally high waves; sea covered with white foam patches; visibility further reduced. |
| 12 | 108-132 | 64-71 | Hurricane | Land:Violent movement of trees and much destruction.
Sea: Air filled with foam; sea completely white with driving spray; visibility greatly reduced. |
| 13 | 133-148 | 72-80 |
| 14 | 149-165 | 81-89 |
| 15 | 166-183 | 90-99 |
| 16 | 184-200 | 100-108 |
| 17 | 201+ | 109+ |
|
1 knot equals 1.15 statute miles per hour
Learn More From These Relevant Books
Chosen by The Weather Doctor
- Gribbin, John and Mary Gribbin: FitzRoy: The Remarkable Story of Darwin's Captain and the Invention of the Weather Forecast, 2004, Yale University Press, New Haven CT, ISBN: 0300103611, 352pp (hc).
- Watts, Alan: Instant Wind Forecasting, 2002, Sheridan House Inc, ISBN 1574091433 (pb).
- Watts, Alan: The Weather Handbook (2nd Edition), 1999, Sheridan House Inc, ISBN 1-57409-081 X .
Written by
Keith C. Heidorn, PhD, THE WEATHER DOCTOR,
January 1, 1998
Beaufort Wind Speed Scale ©1998, Keith C. Heidorn, PhD. All Rights Reserved.
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