Waves Flashcards
What is the coastal systems main source of energy?
Waves
How are waves generated?
Mainly by wind (friction between the wind and surface of the sea) but can be caused by tectonic activity (such as underwater volcanic eruptions that trigger storm surges)
How does wind occur?
Because of the rotation of the earth and difference in atmospheric pressure when different parcels of air are heated differently by the sun
What is the fetch?
The distance of open water the wind blows over (bigger fetch more powerful/big the waves are)
What is the winds strength and duration?
Strength = how forceful the wind is determined by the pressure difference, duration = how long the wind has been blowing for
What is a high tidal range?
Means waves only reach a certain part of the cliff for a small amount of time and therefore less energy is focused on that spot (Eg. Bristol Channel)
What is a low tidal range?
Means waves will be concentrated on a small part of the cliff for longer increasing the energy directed at that point (Eg. Mediterranean)
Explain rip currents:
They transfer energy at the costs, they are localised channels of powerful fast moving water that cut through the breaking waves, they have localised high energy
What are high energy coastlines?
They face powerful waves doe most of the year, erosion exceeds deposition and the landforms reflect this like headlands, arches, caves and wave cut platforms
What are low energy coastlines!p?
Waves are less powerful and the coast is more sheltered, deposition exceeds erosion at these coastlines creating beaches and spits
Explain constructive waves:
Formation = distant weather systems, calm local weather, short fetch (summer) , Wave Form = long weave length, low, spilling waves, Break Characteristics = Strong Swash and weak backwash, Beach = build up the beach, gentle profile (waves have low energy so deposit material)
Explain destructive waves:
Formation = local storms, strong winds, high fetch (winter), Wave Form = short wavelength, high, plunging waves, Break Characteristics = weak swash and strong backwash, Beach = beach is lost, steeper beach profile is likely in the short term, high energy waves erode beach more
What is wave refraction?
Wave energy cone rates at the headland and increases erosion there but reduces amount of energy reaching the bay, waves bend towards the headland as the water depth becomes shallower more quickly, wave breaks and diverges the waves energy, this changes the amount of energy reaching the shore on a small local scale
