Wind force 0 - Calm

Impact on the earth

Calm, smoke rises vertically

Sea state

Sea surface smooth and mirror-like

Speed
  • 0-1 km/h
  • 0-0,54 noeuds (knot)
  • 0 - 0,621 mph
hauteur
  • 0 m
  • 0 ft
 Signe

Wind force 1 - Light Air

Impact on the earth

Smoke drift indicates wind direction, still wind vanes

Sea state

Scaly ripples, no foam crests

Speed
  • 1-5 km/h
  • 0,54-2,7 noeuds (knot)
  • 0,621 - 3,11 mph
hauteur
  • 0 - 0,1 m
  • 0-1 ft
 Signe

Wind force 2 - Light Breeze

Impact on the earth

Wind felt on face, leaves rustle, vanes begin to move

Sea state

Small wavelets, crests glassy, no breaking

Speed
  • 5-11 km/h
  • 2,7-5,9 noeuds (knot)
  • 3,11-6,84 mph
hauteur
  • 0,1 - 0,5 m
  • 1-2 ft
 Signe

Wind force 3 - Gentle Breeze

Impact on the earth

Leaves and small twigs constantly moving, light flags extended

Sea state

Large wavelets, crests begin to break, scattered whitecaps

Speed
  • 11-19 km/h
  • 5.9-10,2 noeuds (knot)
  • 6,84-11,81 mph
hauteur
  • 0,5 - 1,25 m
  • 2-3,5 ft
 Signe

Wind force 4 - Moderate Breeze

Impact on the earth

Dust, leaves, and loose paper lifted, small tree branches move

Sea state

Small waves. becoming longer, numerous whitecaps

Speed
  • 19-28 km/h
  • 10,2-15 noeuds (knot)
  • 11,81-17,4 mph
hauteur
  • 1-2 m
  • 3,5-6 ft
 Signe

Wind force 5 - Fresh Breeze

Impact on the earth

Small trees in leaf begin to sway

Sea state

Moderate waves taking longer form, many whitecaps, some spray

Speed
  • 28-38 km/h
  • 15-20,5 noeuds (knot)
  • 17,4-23,61 mph
hauteur
  • 2-3 m
  • 6-9 ft
 Signe

Wind force 6 - Strong Breeze

Impact on the earth

Larger tree branches moving, whistling in wires

Sea state

Larger waves , whitecaps common, more spray

Speed
  • 38-50 km/h
  • 20,5-27 noeuds (knot)
  • 23,61-31,07 mph
hauteur
  • 3-4 m
  • 9-13 ft
 Signe

Wind force 7 - Near Gale

Impact on the earth

Whole trees moving, resistance felt walking against wind

Sea state

Sea heaps up, waves , white foam streaks off breakers

Speed
  • 50-61 km/h
  • 27-33 noeuds (knot)
  • 31,07-37,9 mph
hauteur
  • 4-5,5 m
  • 13-19 ft
 Signe

Wind force 8 - Gale

Impact on the earth

Whole trees in motion, resistance felt walking against wind

Sea state

Moderately high waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks

Speed
  • 62-74 km/h
  • 33-40 noeuds (knot)
  • 37,9-45,98 mph
hauteur
  • 5,5-7,5 m
  • 18-25 ft
 Signe

Wind force 9 - Strong Gale

Impact on the earth

Slight structural damage occurs, slate blows off roofs

Sea state

High waves, sea begins to roll, dense streaks of foam, spray may reduce visibility

Speed
  • 75-88 km/h
  • 40-47,5 noeuds (knot)
  • 45,98-54,68 mph
hauteur
  • 7-10 m
  • 23-32 ft
 Signe

Wind force 10 - Storm

Impact on the earth

Seldom experienced on land, trees broken or uprooted,considerable structural damage

Sea state

Very high waves with overhanging crests, sea white with densely blown foam, heavy rolling, lowered visibility

Speed
  • 89-102 km/h
  • 47,5-55 noeuds (knot)
  • 54,68-63,38 mph
hauteur
  • 9-12,5 m
  • 29-41 ft
 Signe

Wind force 11 - Violent Storm

Impact on the earth

Widespread devastation

Sea state

Exceptionally high waves, foam patches cover sea, visibility more reduced

Speed
  • 103-117 km/h
  • 55-63 noeuds (knot)
  • 63,38-72,2 mph
hauteur
  • 11,5-16 m
  • 37-52 ft
 Signe

Wind force 12 - Hurricane

Impact on the earth

Considerable destruction

Sea state

Air filled with foam, sea completely white with driving spray, visibility greatly reduced

Speed
  • >118 km/h
  • >63 noeuds (knot)
  • >72,2 mph
hauteur
  • >14 m
  • >46 ft
 Signe