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Beaufort scale

speed of the wind to one height of 10 m on flat land

degree	speed (km/h)	type of wind	speed (knots)	characters	speed (m/s)
0	0 - 1	calm	0 - 1	the smoke rises vertically; the sea is one mirror.	< 0.3
1	1 - 5	puff of wind	1 - 3	the wind turns aside the smoke; ripples of the water.	0.3 - 1.5
2	6 - 11	light breeze	4 - 6	the leaves move; small but obvious waves.	1.6 - 3.3
3	12 - 19	breeze	7 - 10	constantly churned leaves and twigs; small waves,crests that begin to break.	3.4 - 5.4
4	20 - 28	lively breeze	11 - 16	the wind raises powder, leaves sand banks, the coppers is churned; small waves that become longer.	5.5 - 7.9
5	29 - 38	stiff breeze	17 - 21	the shrubs with leaves oscillate; small are formed waves in inner waters; lengthened moderate waves.	8 - 10.7
6	39 - 49	fresh wind	22 - 27	great churned, hissing sound between coppers the telegraphic wires; billow with white foam crests are formed, and sprays.	10.8 - 13.8
7	50 - 61	moderate gale	28 - 33	entire churned trees, difficulty to walk against wind; the sea is large, the foam begins to being frayed in wakes.	13.9 - 17.1
8	62 - 74	moderate squall	34 - 40	broken coppers, to walk against wind are impossible; lengthened billow of medium height and more, from the crests they detach whirlwinds of sprays.	17.2 - 20.7
9	75 - 88	strong squall	41 - 47	removed fireplaces and tiles; large big waves, thick wakes of foam and sprays, raised from the wind, reduce the visibility.	20.8 - 24.4
10	89 - 102	tempest	48 - 55	rare in mainland, trees uprooted, serious damages to the rooms; enormous big waves with long crests to spandrel.	24.5 - 28.4
11	103 - 117	storm	56 - 63	rare, most serious devastations; enormous and high waves, that they can hide ships of medium tonnage; reduced visibility.	28.5 - 32.6
12	over 118	hurricane	64 +	destruction of buildings, manufactured, etc; in sea the foam and the sprays reduce the visibility much.	32.7 +

The speed of the wind is measured with the anemometer, and express in km/h and is suitable from the scale of Beaufort, that takes the name from the admiral British Francis Beaufort (Navam 1774-1857) employed to the service idro-graphic. He in the 1806 proposed a scale for the classification of the strength of the wind in 13 degrees, that came then adopted from the British admiralty in the 1838 and in succession at 1874 o'clock from the rest of the world.

1 kn	= 1.852 km/h
1 kn (UK)	= 1.85318 km/h
1 m/s	= 0.508 (100 feet min.)
100 feet min.	= 1.9685 m/s

compass card

direction	wind	international symbol
NORTH	tramontana or north wind	N
NORTH-EAST	greco, gregale or northeast wind	NE
EAST	levante or eastrly wind	E
SOUTH-EAST	sirocco	SE
SOUTH	auster or south wind	S
SOUTH-WEST	libeccio, garbino or southwest wind	SW
WEST	ponente, espero or west wind	W
NORTH-WEST	maestro, maestrale, mistral or northwest wind	NW

any definitions of speed and distance

knot, international (kt)	= 0.514444 m/s
knot (imperial knot)	= 0.514772 m/s
knot (US knot)	= 0.514791 m/s
1 mile nautical/h	= 1 knot
1 MACH	= 1228 km/h

mile nautical international	= 1852 m
mile nautical italian	= 1851.85 m
geografic mile	= 1855.4 m
mile UK (nautical)	= 1853.184 m
mile US (nautical)	= 1852 m

an outline of the knot

The historical origin of this measure goes back to the sailing-ship age. When the commander of a clipper wanted to know the own speed, it made to spin to breast one line, on which they were present of the nodes distanced between they of 1/120 of mile (15.433m). To the extremity of the sunk line, a tablet (log-chip), that it acted as from floating anchor. In such a way while the sailing-ship was left over, the line carried out outboard motor making to parade a node after the other, therefore after 30 minuteren of hourglass (30 ") came counted how many nodes were past, than therefore represented with a lot approximation the speed of the ship.

Douglas scale

	denomination	height waves (m)
0	calm	0
1	nearly calm	< 0.1
2	little moved	0.1 - 0.5
3	moved	0.5 - 1.3
4	a lot moved	1.3 - 2.5
5	rough	2.5 - 4
6	much rough	4 - 6
7	flood	6 - 9
8	much flood	9 - 14
9	stormy	> 14