Wave Height – Beaufort Scale

Sea like a mirror.

Ripples with the appearance of scales are formed, but without foam crests.

Small wavelets, still short, but more pronounced. Crests have a glassy appearance and do not break.

Large wavelets. Crests begin to break. Foam of glassy appearance. Perhaps scattered white horses.

Small waves, becoming larger; fairly frequent white horses.

Moderate waves, taking a more pronounced long form; many white horses are formed.

Large waves begin to form; the white foam crests are more extensive everywhere.

Moderately high waves of greater length; edges of crests begin to break into spindrift. The foam is blown in well-marked streaks along the direction of the wind.

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

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 on a white appearance. The tumbling of the sea becomes heavy and shock-like. Visibility affected.

Exceptionally high waves (small and medium-size 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.

The air is filled with foam and spray. Sea completely white with driving spray; visibility very seriously affected.

Sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind.