Beaufort specifications for use at Sea and on Land:
0
SEA: Sea like a mirror.
LAND: Calm, smoke rises vertically.
1
SEA: Ripples with the appearance of scales formed but without foam crests.
LAND: Direction of wind shown by smoke drift but not by wind vanes.
2
SEA: Small wavelets, still short but more pronounced; crests have a glassy appearance and do not break.
LAND: Wind felt on face; leaves rustle; ordinary vane moved by wind.
3
SEA: Large wavelets; crests begin to break; foam of glassy appearance; perhaps scattered white horses.
LAND: Leaves and small twigs in constant motion; wind extends light flag
4
SEA: Small waves, becoming longer; fairly frequent white horses.
LAND: Raises dust and loose paper; small branches moved.
5
SEA: Moderate waves, taking a more pronounced long form; many white horses are formed; chance of some spray.
LAND: Small trees in leaf begin to sway; crested wavelets form on inland waters.
6
SEA: Large waves begin to form; the white foam crests are more extensive everywhere; probably some spray
LAND: Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty.
7
SEA: Sea heaps up and white foam from breaking waves begin to be blown in streaks along the direction of the wind
LAND: Whole trees in motion; inconvenience felt when walking against wind.
8
SEA: Moderately high waves of greater length; edges of crests begin to break into spin-drift; the foam is blown in well-marked streaks along the direction of the wind.
LAND: Breaks twigs off trees; generally impedes progress.
9
SEA: High waves; dense streaks of foam along the direction of the wind; crests of waves begin to topple, tumble, and roll over; spray may affect visibility.
LAND: Slight structural damage occurs (chimney-pots and slates removed).
10
SEA: Very high waves with long overhanging crests; the resulting foam, in great patches, is blown in dense white streaks along the direction of the wind; on the whole, the surface of the sea takes a white appearance; the tumbling of the sea becomes heavy and shock-like; visibility affected.
LAND: Seldom experienced inland; trees uprooted; considerable structural damage occurs.
11
SEA: Exceptionally high waves (small and medium-sized ships might be for a time lost to view behind the waves); the sea is completely covered with long white patches of foam lying along the direction of the wind; everywhere the edges of the wave crests are blown into froth; visibility affected.
LAND: Very rarely experienced; accompanied by widespread damage.
12
SEA: The air is filled with foam and spray; sea completely white with driving spray; visibility very seriously affected.