Wave Terms Explained

There is a lot of associated terminology when talking about waves. It's handy to know what it all means if you want to start forecasting your own surf. If you are looking to increase your own general surf vocabulary then take a look at the surfing terminology section. OK, let's get cracking.

Glossary of Wave Terms

The Main Wave Features

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. One of the highlights for any surfer is catching a tube ride.

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 sea (baby swell!)

Chop
Moderate local winds form little waves known as chop - this can kill a good surf session. Also know as Wind Chop.

Closeout
A wave that breaks along its entire length at the same time making it unsurfable. 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. See this corduroy swell picture that illustrates it perfectly.

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.

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 or a slight offshore wind. Have a look at this picture of a glassy Huntingdon Beach wave.

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

Left
A 'Left' is a wave that breaks from left to right as you are looking from the beach.

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 occuring then the gravitational pull of the Sun and Moon are at right angles to the Earth.

Offshore Wave
This in surfing terms relates to the wind blowing from the shore. A ground swell mixed with offshore winds makes for cracking surf.

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.

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.

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.

Refraction of Waves

Right
A Right is a wave that breaks from right to left when viewed from the beach.

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.

Spring Tide
Larger than normal tides occuring 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 (tadaa!).

Surf Zone
The area from the shore out to where the waves start breaking (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
The foamy part of a wave that has broken.