|Beaufort scale number
||Units in km/h
||Units in knots
||Description on Land
||Description at Sea
||Smoke rises vertically
||Sea like a mirror.
||19 km/h or less
||10 knots or less
||Wind felt on face; leaves rustle; ordinary vanes moved by wind.
||Small wavelets, ripples formed but do not break: A glassy appearancemaintained.
||20 - 29 km/h
||Raises dust and loose paper; small branches are moved.
||Small waves - becoming longer; fairly frequent white horses.
||30 - 39 km/h
||Small trees in leaf begin to sway; crested wavelets form on inland waters
||Moderate waves, taking a more pronounced long form; many white horses are formed - a chance ofsome spray
||40 - 50 km/h
||Large branches in motion; whistling heard in telephone wires; umbrellas used withdifficulty.
||Large waves begin to form; the white foam crests are more extensive with probably somespray
||51 - 62 km/h
||Whole trees in motion; inconvenience felt when walking against wind.
||Sea heaps up and white foam from breaking waves begins to be blown in streaks along direction ofwind.
||63 - 75 km/h
||Twigs break off trees; progress generally impeded.
||Moderately high waves of greater length; edges of crests begin to break into spindrift; foam isblown in well-marked streaks along
the direction of the wind.
||76 - 87 km/h
||Slight structural damage occurs -roofing dislodged; larger branches break off.
||High waves; dense streaks of foam; crests of waves begin to topple, tumble and roll over; spraymay affect visibility.
||88 - 102 km/h
||Seldom experienced inland; trees uprooted; considerable structural damage.
||Very high waves with long overhanging crests; the resulting foam in great patches is blown indense white streaks; the surface of
the sea takes on a white appearance; the tumbling of the seabecomes heavy with visibility affected.
||103 -117 km/h
||Very rarely experienced - widespread damage
||Exceptionally high waves; small and medium sized ships occasionally lost from view behind waves;the sea is completely covered with
long white patches of foam; the edges of wave crests are blowninto froth.
||118 km/h or more
||64 knots or more
||The air is filled with foam and spray. Sea completely white with driving spray; visibility veryseriously affected