Wave Terminology Explained

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Amplitude
The vertical distance from still water level to wave peak (half the height of the wave).

Barrel
The same as Tube. The hollow part of a breaking wave where there is a gap between the face of the wave and the lip of the wave as it curls over. Every surfer loves a barrel. Also known as the “Green Room”

Bathymetry
The features of the sea floor. The measurement of water depth at various places in a body of water.

Capillary Waves
The first small waves created when the wind blows on the ocean.

Chop
Moderate local winds form little waves known as chop. This can be very frustrating. Also known as Wind Chop.

Closeout
A wave that breaks along its entire length at the same time making it unsurfable and sometimes unsafe. Closeouts can either be caused by a strong offshore wind or sea floor topography. Also called shutting down.

Corduroy
Swell lines that look like corduroy.

Crest
The highest part of the wave (above still water level). Same as the Wave Peak.

Crumble / Crumbly Waves
Waves affected by an onshore wind are said to crumble. The lip of the waves will ‘crumble’ along the line and as a result spoil the waves for surfers.

Decay of Waves / Wave Decay
The decrease in wave height and increase in wavelength of a wave once it is outside the fetch.

Diffraction
When the wave comes into contact with an obstacle or barrier such as a breakwater, the energy of the wave is transmitted along a wave crest. Diffraction is the ‘spreading’ of waves into the sheltered region within the barrier’s geometric shadow.

Doubles / Doubling up
When waves are so close together near the shore, that the one behind actually surpasses the one in front and “Doubles Up” on it, forming one large wave.

Fetch
The area of sea surface where the wind generates the waves / swell. Fetch is one of the key areas in the quality of a swell and the size of the waves.

Fully Developed Sea
Waves that have reached the maximum size possible for a fetch, wind speed and wind duration.

Glassy
Waves that have incredibly smooth faces due to the lack of local wind.

Green water
The unbroken peeling part of a wave that is usually green, sometimes blue.

Green room
The inside of the barrel or tube.

Ground Swell
Waves no longer being affected by the winds that generated them. Waves outside the Fetch.

Left
A ‘Left’ is a wave that a surfer can ride going left. (Breaks to the left from the peak)

Lip
The upper most part of the breaking wave where a surfer will do maneuvers such as a floater.

Neap Tide
Smaller than normal tides occurring then the gravitational pull of the Sun and Moon are at right angles to the Earth.

Offshore Wave
Waves formed by offshore winds. Also known as waves that are much farther off shore.

Onshore Waves
The opposite to offshore. The wind blows toward the beach and as a result the waves lose their shape and crumble.

Peak
The highest part of the wave (above still water level). Same as the Crest. The peak is where the wave will be breaking or peeling.

Peak Direction
The wave direction at the frequency at which a wave spectrum reaches its maximum.

Peak Period / Wave Period
The time taken for consecutive wave crests or wave troughs to pass a given point. The greater the wave period the better the swell.

Period
The time interval between one wave and the next wave. There may also be longer time period between sets.

Refraction
The tendency of wave crests to become parallel to underwater contours as waves move into shallower waters. Waves moving in shallow waters move more slowly than waves moving in deeper water. Refraction can be seen where waves ‘wrap’ round a point and their direction seems to change.

Right
A Right is a wave that a surfer can ride going right. (Breaks to the right from the peak)

Sets
Small waves can be coming in every 20 seconds, but good rideable waves may only come every 20 min. These waves usually come in a group called a set.

Significant Wave Height
How significant are your wave heights? You are likely to have seen significant wave height on surf reports. The Significant Wave Height is the average height of the one-third highest waves of a given wave group.

Shoaling
Waves being forced to bunch together as they enter shallower water and slow down. This can cause doubles, or doubling up.

Spring Tide
Larger than normal tides occurring when the gravitational pull of the Sun and Moon are combined in line. The opposite effect to Neap Tides.

Surf
Waves breaking near the shore.

Surf Zone
The area from the shore out to where the waves start breaking which is called “the line up”.

Tide
The increase and decrease in sea level resulting from the Moon’s and to a lesser extent Sun’s gravitational pull.

Trough
The lowest part between two successive waves (or the part between two successive waves below still water level).

Tube
The hollow part of a breaking wave where there is a gap between the face of the wave and the lip of the wave as it curls over.

Wave Direction / Swell Direction
The direction from where the waves approach (not the direction in which they are heading). If a surf spot works on a Northerly this refers to a Northerly Swell Direction.

Wavelength
The distance between two points two corresponding points on successive waves (e.g. the distance between two peaks).

Whitewater / Whitewash
The white foamy part of a wave that has broken.

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