Wind:
Aeolian energy is the primary source for other processes. Influence wave type created by
frictional drag of wind on water. Fetch is the distance of open water the wind blows over
and prevailing wind is the most frequent wind direction.
Waves:
• Formation = caused by friction of the wind onto the sea, higher layers of wind move
faster and fall forwards to create a wave. Wind blows behind the ripple, causing it to
grow.
• Breaking = As a wave approaches the shore and water depth decreases, wavelength
shortens and wave height increases. Circular motion turns elliptical as friction
increases. At steepness ratio 1:7 the wave collapses.
Can be spilling (steep waves on gently sloping beaches), plunging (Steep waves on
steep beaches) or surging (low-angle waves on steep beaches)
• Wave Refraction = Process by which waves break onto an irregularly shaped
coastline (headlands). Increased friction in shallower water causes wave to become
high steep and short as it slows. Wave refracts around headland and orthogonals
converge to concentrate wave energy.
Tides:
• Tidal Cycles =The periodic rise and fall of the sea surface produced by the
gravitational pull of the moon (and sun to a lesser extent).
Spring Tide – Every 15 days maximum tidal range when the moon, earth and sun are
all aligned to create the strongest gravitational pull. The moon pulls water towards it
creating a high tide on both sides of the Earth with a low tide between them.
Neap Tide – When the moon and sun are at right angles the gravitational pull is
partly counterbalanced. Lowest tidal range.
• Tidal Range = The vertical difference between high and low tide which influences
where wave action occurs, the weathering processes and scouring between tides
(coastline development).
Mediterranean – low (0.01m)
Severn Estuary – high (14m)
Geology:
• Lithology = The physical and chemical composition of rocks. Clay is weak and faster
eroding than resistant basalt rocks of dense interlocking crystals. Chalk and
carboniferous limestone are vulnerable to chemical weathering due to calcium
carbonate which is soluble in weak acids.
• Structure = Features of jointing, faulting, permeability (ability to absorb water) and
bedding planes in the rock. Chalk has primary permeability in pores, limestone has
secondary permeability in joints.
Concordant – Rocks parallel to coast
Discordant – Rocks at right angles to coast (headlands and bays common)
Strata angle – Horizontally bedded and landward-dipping strata creates steep cliffs,
whilst seaward inclined strata cliffs follow the dip angle.
Ocean Currents:
The permanent or seasonal movement of water in seas and oceans.
• Longshore Currents = Most currents approach the shoreline at an angle, creating a
current of water running parallel to the shoreline. Transports sediment parallel to
shoreline.
• Rip currents = Strong currents moving away from the shoreline due to a build-up of
seawater and energy along the coastline.
• Upwelling = Global pattern of currents circulating in the oceans can cause deep, cold
water to move towards the surface, displacing the warmer surface water.
Generated by the Earth’s anticlockwise rotation which deflects winds right in the
northern hemisphere and left in the southern. Warm currents transfer heat from low
to high latitudes which affects air temperature and thus, sub-aerial processes.
Tidal energy dominates in estuarine environments, wind energy in dune environments, etc.