Wind - Wind Force Scale

Wind Force Scale

See also: Tropical cyclone scales and Surface weather analysis

Historically, the Beaufort wind force scale provides an empirical description of wind speed based on observed sea conditions. Originally it was a 13-level scale, but during the 1940s, the scale was expanded to 17 levels. There are general terms that differentiate winds of different average speeds such as a breeze, a gale, a storm, tornado, or a hurricane. Within the Beaufort scale, gale-force winds lie between 28 knots (52 km/h) and 55 knots (102 km/h) with preceding adjectives such as moderate, fresh, strong, and whole used to differentiate the wind's strength within the gale category. A storm has winds of 56 knots (104 km/h) to 63 knots (117 km/h). The terminology for tropical cyclones differs from one region to another globally. Most ocean basins use the average wind speed to determine the tropical cyclone's category. Below is a summary of the classifications used by Regional Specialized Meteorological Centers worldwide:

General wind classifications			Tropical cyclone classifications (all winds are 10-minute averages)
Beaufort scale	10-minute sustained winds (knots)	General term	N Indian Ocean IMD	SW Indian Ocean MF	Australian region South Pacific BoM, BMKG, FMS, MSNZ	NW Pacific JMA	NW Pacific JTWC	NE Pacific & N Atlantic NHC & CPHC
0	<1	Calm	Low Pressure Area	Tropical disturbance	Tropical low Tropical Depression	Tropical depression	Tropical depression	Tropical depression
1	1–3	Light air
2	4–6	Light breeze
3	7–10	Gentle breeze
4	11–16	Moderate breeze
5	17–21	Fresh breeze	Depression
6	22–27	Strong breeze
7	28–29	Moderate gale	Deep depression	Tropical depression
	30–33
8	34–40	Fresh gale	Cyclonic storm	Moderate tropical storm	Tropical cyclone (1)	Tropical storm	Tropical storm	Tropical storm
9	41–47	Strong gale
10	48–55	Whole gale	Severe cyclonic storm	Severe tropical storm	Tropical cyclone (2)	Severe tropical storm
11	56–63	Storm
12	64–72	Hurricane	Very severe cyclonic storm	Tropical cyclone	Severe tropical cyclone (3)	Typhoon	Typhoon	Hurricane (1)
13	73–85							Hurricane (2)
14	86–89				Severe tropical cyclone (4)			Major hurricane (3)
15	90–99			Intense tropical cyclone
16	100–106							Major hurricane (4)
17	107–114				Severe tropical cyclone (5)
	115–119			Very intense tropical cyclone			Super typhoon
	>120		Super cyclonic storm					Major hurricane (5)