L2 waves

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L2 waves

  1. 1. How do waves influence erosion? Key questions: • What are constructive + destructive waves? • How do waves influence erosion?
  2. 2. How do waves work? What causes waves?
  3. 3. How do waves work? • Waves are created by wind • The friction of the wind makes the sea swell and rise up • The energy of the wind causes water particles inside the sea to rotate and this movement pushes the wave forward • The waves get bigger until they reach the coast where they break
  4. 4. Waves
  5. 5. Coastal processes • Bitesize coastal processes
  6. 6. Geog.GCSE • P88 • Make a large, neat copy of the diagram on p88. • Add short labels
  7. 7. The sea drains back down the beach. This is called backwash. This process moves material back down the beach. Within each individual wave, the water particles all move in a circular motion. A constant circle back to their starting points. When a wave moves in to shallow water near the coastline it starts to rear up and distort until it breaks. Out at sea, sometimes thousands of miles away, the wind is blowing. As the wind blows across the surface of the sea it creates friction. It tugs across the sea and causes the wave shape to move forwards. Once the wave breaks, there is energy moving and also water crashing forwards. This provides the energy for erosion and deposition. Water from the sea rushes up the beach. This is called the swash. This process moves material up the beach.
  8. 8. The sea drains back down the beach. This is called backwash. This process moves material back down the beach. Within each individual wave, the water particles all move in a circular motion. A constant circle back to their starting points. When a wave moves in to shallow water near the coastline it starts to rear up and distort until it breaks. Out at sea, sometimes thousands of miles away, the wind is blowing. As the wind blows across the surface of the sea it creates friction. It tugs across the sea and causes the wave shape to Once the wave breaks, there is energy moving and also water crashing forwards. This provides the energy for erosion and deposition. Water from the sea rushes up the beach. This is called the swash. This process moves material up the beach. 6 1 2 3 4 5
  9. 9. Waves keywords • Swash = the wave washing up the beach. • Backwash = the wave pulling back down the beach by gravity. • The crest = is the top of the curling wave, the wave at its highest point. • The fetch = is the distance a wave travels before it crashes on to the coastline. • A constructive wave = helps to build a beach. • A destructive wave = erodes a beach.
  10. 10. Why are some waves stronger than others? Geog.gcse p88. Complete these Qs in sentences. 1. The height and strength of waves depend on i)................ii)................iii)................... 2. What is the ‘fetch’? 3. What winds affect our south coast in Britain? 4. South-westerly winds produce ....................... waves because ........................... 5. South-easterly winds produce .............................. waves because ........................... 6. What is more important, fetch or wind speed?
  11. 11. Fetch Brazil Atlantic Ocean France English channel
  12. 12. Why do waves break? • Why do you think waves break when they reach a beach?
  13. 13. Characteristics of Waves crest Fetch
  14. 14. Waves • There are two main types of waves: • Constructive vs Destructive
  15. 15. Constructive vs Destructive • Geog.gcse p89 or Tomorrow’s Geog p5 • Copy the diagrams of the two types. • You must include the information too
  16. 16. Constructive Waves Gently sloping wave Wave crests far apart Breaking wave spills, does not crash Gentle beach
  17. 17. Destructive Waves Steeply sloping wave Breaking wave plunges + crashes Waves close together
  18. 18. Quick test • Which waves builds up the beach? • Which wave has a stronger backwash? • Which wave has low wave height? • Constructive waves usually happen on gentle or steep slope beaches? Why? • Destructive waves are ‘spilling’ or ‘breaking’?
  19. 19. Waves + the coast • Not only do waves erode the coast, they also transport and deposit the material that they erode to different places • Southsea beach may have been eroded and transported there from France • How do waves transport material?
  20. 20. Long-shore drift (LSD)
  21. 21. Exam Q 1) Describe and explain how constructive and destructive waves work. Use keywords or examples where possible. [4marks] 2) Apart from the strength of waves, what other factors can effect how quickly a coastline erodes? [3marks]

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