Waves and tides

• Earth experiences a squeeze which causes tidal bulges on both sides.
• Waves can be generated by tectonic activity but are mostly made by wind.
• Wind moves from high to low pressure.
• A greater pressure gradient results in faster and stronger winds.
• In the UK, the prevailing winds blow from the south-west.
• Factors which affect wave energy include the strength of the wind, duration of the wind and the fetch
• Water becomes shallower and the circular orbit changes to an elliptical shape during wave formation.
• Wavelength and velocity decrease and height increases during wave formation, causing water to rise and topple over.
• Waves are integral to how other landforms and coastal processes occur, ultimately shaping the coastline.
• Constructive waves build beaches up over time, but over time the profile steepens and the waves turn destructive, removing material, resulting in a less steep profile encouraging constructive waves.
• Tides are changes in the water level caused by the gravitational pull of the moon.
• At a neap tide, the moon is at right angles to the sun, creating a smaller tidal range.
• At a spring tide, the sun and moon are in line, creating a larger tidal range.
• High tidal range = powerful tidal currents, which are important in transporting sediment.
• High tidal range means there is a specific level for a short period of time.
• The littoral zone includes the backshore, nearshore and offshore.
• Rate of deposition exceeds erosion in sandy coasts.
• Landforms associated with low energy coastlines include beaches and spits.
• Offshore is an area further seaward than nearshore.
• Wave refraction is the bending of waves as they approach the coastline.
• Wave refraction causes energy to be concentrated at headlands and dissipated at bays.
• The moon's gravity is weaker but the pull of gravity is significant.
• Orbits become elliptical through bed friction in shallow water.
• Landforms associated with high energy coastlines include headlands, cliffs and wave-cut platforms.
• Rocky coasts are high energy coastlines.
• The moon has a tidal force on earth's water in the direction of the moon.
• The water particles move forward until the crest breaks in the open sea.
• In the open sea, water particles are in orbit.
• A bulge towards the moon is a high tide.
• Low tidal range means erosion is concentrated on a small section for a long period of time.
• Backshore is an area from the mean high water mark up to the change in geography.
• Erosion is concentrated at either side of a high tide, creating a wave-cut notch.
• Crest: highest part of the wave
• Trough: lowest point under surface
• Wave height: overall vertical change in height between crest and trough ( 2 x amplitude)
• Wavelength: distance between 2 successive crests
• Period: time required for 2 successive crests or troughs to pass a point
• Frequency: number of peaks or troughs to pass a point
• Steepness: wave height divided by wave length