10.1 Coastal landscapes Flashcards
(9 cards)
How does a wave get to the beach
- Sea waves are foward-moving surges of energy
- In deep water waves move in circular motion
- As the wave approached the sea bed this motion is interrupted and the wave movement becomes elliptical. There is friction with the seabed
- As the seabed incline gets steeper, the top of the wave moves faster
- The orbit becomes increasingly elliptical until the wave breaks
- The water rushes up to the beach and water from the previous washes down the beach
What does it mean for the fetch and power if the wave is far away
The longer the fetch and the strong the power because it has picked up speed from the wind as it travels
Describe a constructive wave
- spilling waves
- strong swash
- 6-8 waves per minute
- Low wavelength and less than 1m high
Describe a destructive wave
- Plunging waves
- Strong backwash destroys cliffs and beaches in the winter
- 13-15 waves per minute
- Higher wavelength usually 6m
What affects the power of a wave?
- The speed of the wind
- The distance a wave has travelled (fetch)
- The type of wave (constructive or destructive)
What is prevailing wind
The direction from which the wind usually comes from
What angle is the backwash to the beach
90 degrees
Compare the characteristics of contrastive and destructive waves (4 marks)
Constructive waves
- involved in the transportation of sand, pebbles and deposit sediment
- have a strong swash
- due to dissipation of wave energy by the beach, the backwash is weak
- most common during the summer months
Destructive waves
- plunging waves which closely follow one another and are stronger than constructive
- approximately 10-15 waves per minute, more common in winter
- attack cliffs (often more than 6 metres high)
- powerful backwash carries sediment away
How are waves formed
From friction between wind and sea surface
