What is a crest?
Highest point of the wave
What is a trough?
Lowest point of the wave
What is backwash?
Any water returning down to the sea
What is wave height?
The distance between the crest and the trough, rarely exceeds 6 metres unless storm conditions
What is the swell?
Waves of low height, gentle steepness, long wave length and period
What is wave velocity?
Is the speed of movement of a crest in a given period of time
What is wave steepness?
Is the ratio of the wave height to wave length
What is the wave period?
Time taken for a wave to travel through one wave length
What is the plunge line?
The point where the wave breaks
What is the swash?
The body of foaming water rushing up the beach
What is the wave length?
The distance between two successive crests
Waves are the…to the coastal system and created by…
- main input of energy to a coastal system
- created by energy transfer from the wind
The wave size increases as…
The strength of wind increases
When the wave approaches the shore the speed of water at the top of the wave…
Exceeds that of the rest of the wave so it toppled over and breaks due to friction
The part of the wave toppling over is…
Twice as fast as the rest of the wave
The energy obtained by waves depends on…
- wind velocity
- length of the fetch
- period of time during which the wind has blown
- depth of water
What is the fetch?
Maximum distance of open water over which wind can blow. Places of greatest fetch receive highest energy waves
How does water depth effect waves reaching shore?
Shallow water offshore reduces the energy reaching the coast
Waves that travel short distances are a result of…and are known as…?
Local winds and known as Sea waves
Waves that travel longer distances are formed by… and known as…?
Distant storms and known as swell waves
What’s is Britain mainly affected by and where?
Britain is mainly affected by sea waves but swell waves occur in Cornwall as the coast faces open ocean
What is a constructive wave?
- created in calm weather conditions
- depositional wave
- powerful swash weak backwash
- common when long fetch exists
- long, low gradient, may not break
- 6-9 per minute frequency
What are destructive waves?
- created in storm, winter conditions
- less swash greater backwash
- destroy beach, erosive
- tall so create steep narrow beaches
- high in proportion to length which is short
- frequency is 12-15 per minute
What is wave refraction?
- occurs along a discordant coastline
- headland is hard more resistant rock and bay is soft less resistant rock
- when waves approach the coastline that isn’t a regular shape they are refracted and become increasingly parallel to the coastline
- as waves reach the shore the drag in shallower water which meets the headland
- this causes the waves to become higher and steeper with a shorter wave length
- the part of the wave in deeper water moves forward faster causing the wave to bend
- the overall effect is that the wave energy becomes concentrated at the headland causing greater erosion there (erosion process)
- low energy waves spill into the bay causing beach deposition
