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Sat 17 Nov 18 #1 

Beaufort Wind Scale

The Beaufort scale of wind force was developed in 1805 by British navy officer and hydrographer Francis Beaufort. It is not based on instrumental measurement but on observation alone.

0 -- Calm -- 0knots 0 km/h (0mph). Sea glassy. Smoke rises vertically.

1 -- Light air -- 1-3 knots 2-5km/h (1-3mph). Sea lightly rippled. Direction shown by smoke drift but not by wind vanes.

2-- Light breeze -- 4-6 knots 6-11 km/h (4-7 mph). Small wavelets; crests do not break. Wind felt on face; leaves rustle; wind vanes moved by wind; flags wave slightly.

3 -- Gentle breeze -- 7-10 knots 12-19 km/h (8-12 mph). Large wavelets; crests begin to break; possible scattered white horses. Leaves and twigs in constant motion; light flags extended.

4 -- Moderate breeze -- 11-16 knots 20-29 km/h (13-18 mph). Small waves becoming longer; fairly frequent white horses. Raises dust and loose paper; small branches moved; flags flap.

5 -- Fresh breeze -- 17-21 knots 30-39 km/h (19-24mph). Moderate waves taking a more pronounced long form; many white horses; the chance of some spray. Small trees in leaf begin to sway; crested wavelets form on inland waters.

6 -- Strong breeze -- 22-27 knots 40-50 km/h (25-31mph) . Large waves form; white foam crests more extensive; probably some spray. Large branches in motion; whistling heard in telephone and overhead power lines; umbrellas used with difficulty.

7 -- Moderate gale/Near gale -- 28-33 knots 51-62 km/h (32-38 mph). Whole trees in motion; inconvenience felt when walking against the wind. Sea heaps up; foam blown in streaks along direction of wind; spindrift begins to be seen.

8 -- Gale/Fresh gale -- 34-40 knots 63-75 km/h (39-46 mph). Moderately high waves; edges of crests break in to spindrift; foam is blown in well marked streaks along the direction of the wind. Twigs break off trees; progress generally impeded.

9 -- Strong gale/Severe gale -- 41-47 knots 76-87 km/h (47-54mph). High waves; sea begins to roll; spray affects visibility. Branches break off trees; slight structural damage, roofing dislodged.

10 -- Storm/Whole gale-- 48-55 knots 88-102 km/h (55-63 mph). Very high waves with long overhanging crests; sea takes on white appearance; heavy rolling of the sea. Seldom experienced inland; trees uprooted; considerable structural damage.

11 -- Violent Storm -- 56-63 knots 103-117 km/h (64-72mph). Exceptionally high waves;small and medium sized ships occasionally lost from view behind waves; edges of wave crests blown into froth. Rarely experienced inland; widespread damage.

12 -- Hurricane --  64 knots or more 118 km/h or more (75 mph or more). Air filled with foam and spray; sea completely white with driving spray; visibility seriuosly affected. Very rarely experienced inland; severe and extensive damage.

Sources : Bureau of Meteorology Australia; Royal Meteorological society; Wikipedia

Questions could be:
X on the Beaufort Scale describes which conditions
Y describes which Beaufort Scale rating
Which conditons are rated X on the Beaufort Scale

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Mon 19 Nov 18 #2 

Thanks for this chooky. Funnily enough I though we already had this one but obviously we don't. I am a bit distracted at the moment with family matters but will get it (and the others you posted) in as soon as I can.

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Wed 21 Nov 18 #3 

No rush JMK, happy to wait.  : )

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Thu 29 Nov 18 #4 

Coming in to relieve JMK.  Subject has been added.  Thank you.

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Sat 1 Dec 18 #5 

Thanks Java : )

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