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)

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