In Geography, waves occur in oceans, and are very important in the coastal system. They occur because of friction between the sea and the wind. The wind makes fetch happen! There are two types of waves:
Constuctive waves Edit
- Deposits material
- Never operate in summer (when the wind isn't as weak and the waves are rougher)
- Breaks strongly, then swashes up the beach
- Strong swash
- Weak backwash
- 5-6 waves/minute
- 1m high
- longer wave-length
- and lower wave frequency
- Mainly erode
- Operate in storm conditions (most common in winter)
- Created from big, strong waves when the wind is strong and has been blowing for a long time
- Occur when wave energy is high and the wave has travelled for a long time
- Tend to remove material from the coast and associated with erosion
- Backwash is stronger than the swash.
- 5-6m high
- Steep sloped sandy beach
- Wave frequency 10-15 per min
- Fetch distance shorter
Formation of WavesEdit
Waves form because of the friction between the wind and the sea. The areas of high pressure become troughs and the areas of low pressure become the wave crests.
Waves break when they are too steep to maintain their height. Near the coast waves steepen because of a fall in velocity because of friction with the seabed or in a much easier way Breaking waves is when the wave is too high and it hits
Wave energy is generally affected by three main factors:
- Wind speed - higher wind speed means more wave energy, because the energy is transfered from the wind to the wave.
- Fetch - the distance of open water over which the wave has travelled across makes a big differenece on wave height and wave energy, as a longer fetch gives the waves longer to 'grow'.
- Wind duration - with a longer storm, the waves will be bigger.
Wave energy and coastal enviromentEdit
How much energy the waves have will change how the coast looks:
- High wave energy --> jagged cliffs, rocky coastlines, large boulders
- Example: Cornwall
- Medium wave energy --> sandy beaches, spits
- Example: S.Coast
- Low wave energy --> mudflats, salt marshes
- Example: Norfolk coast
Wind makes fetch happenEdit
Wind blows across the surface of the water, this is what creates fetch.