Coasts

• Atmosphere


  the air that surrounds the Earth, made up of gases and water vapour
• Lithosphere


  the crust and uppermost mantle
• Hydrosphere


  a discontinous layer of water at or near the Earth's surface, It includes all liquid and frozen surface waters, groundwater held in soil and rock, and atmospheric water vapour
• Biosphere


  the total sum of all living matter. the biological component of the Earth's systems
• Isolated systems


  no input/output of energy or matter - some suggest the universe is the only example of this, others claim it is not applicable in geography
• Closed systems


  input, transfer and output of energy but not matter

  a system in which the amount of matter remains constant but in which energy can be transferred as an input, output of flow
• Open systems


  inputs, outputs of both energy and matter

  a system in which energy and matter can be transferred in, through and out
• Input

  energy and/or matter entering a system
• Output

  energy and/or matter leaving a system
• store/component


  a section of a syste in which matter can remain, be added to or be removed from
• flow/transfer


  movemenet between stores/components in a system
• boundary

  the edge of a particular system
• dynamic equilibrium


  when the inputs and outputs in a system are balanced and the stores remain the same

  when something from outside the system causes a change and acts on that system the dynamic equilibrium will be upset and the system will no longer be in balance

  this causes feedback
• Negative feedback


  when a system acts by lessening the effect of the original change and ultimately reversing it

  it is negative feedback as the increase in temperature eventually leads to a decrease in temperature
• Positive feedback


  occurs within a system where a change causes a further or snowball effect, continuing or even accelerating the original effect; the effects are amplified

  it is positive feedback as the increase in temperature causes further increases in temperature
• Marine factors

  waves, winds, tides, salt spray, currents
• Subaerial factors


  temperatures, weather - rain, winds, snow, frost, sun
• Human factors


  pollution, conservation management, buildings, recreation
• Geomorphic factors

  rivers, glaciers, mass movement
• Biotic factors


  impact of vegetation, coral reefs etc
• Geology


  structure and lithology (rock type)
• Tectonics


  coastal uplift, volcanic activity
• Climatic factors


  winds - generate waves and currents

  weather - affects weathering of cliffs, sources of beach material

  climate change

  glaciation - changes in sea level eustatic/isostatic
• Prevailing wind


  the direction from which the wind most commonly blows
• How are waves formed

  As air moves across the water frictional drag disturbs the surface and forms ripples or waves. In open sea there is little horizontal movement of water. Instead there is an orbital motion of the water particles. Close to the coast, horizontal movement of water does occur as waves are driven onshore to break on the beach
• Waves breaking


  The water becomes shallower and the circular orbit of the wave particles changes to an eliptical shape

  The wavelength and the velocity both decrease and the wave height increases - causing water to break up from behind and rise to a point where it starts to topple over (break)

  the water rushes up the beach as swash and flows back as backwash
• Fetch


  the distance of open water over which the wind blows
• wave energy is determined by

  strength of wind

  duration of wind

  fetch
• Wave crest


  the highest surface part of a wave
• Wave trough


  the lowest part of the wave between crests
• Wave height


  the height difference between a wave crest and the neighbouring trough
• Wavelength/amplitude


  the distance between successive crests
• Wave period


  the time in seconds between two successive crests or troughs
• Wave frequency


  the number of waves per minute
• Swash


  the rush of water up to the beach after a wave breaks
• Backwash


  The action of water receeding back down the beach to the sea
• Swell waves

  waves in open water, characterised by long wavelengths and reduced height. They can reach up to 15m high and can travel huge distances
• Storm waves

  Waves are generated by local winds which travel only short distances (these are the waves you might see near the coast
• Constructive waves


  formation: distant weather systems generate these waves in the open ocean

  wave form/shape: low surging waves with a long wavelength

  breaking characteristsics: strong swash, weak backwash

  net effect on beach: beach gain

  beach profile: usually associated with a gentle beach profile - althought - builds up over time and gets steeper

  wavelength: up to 100m

  wave frequency: (low) 6-8 per minute

  wave period: (high) one every 8-10 seconds

  also known as: swell or surging waves
• Destructive waves


  formation: local storms are responsible for these waves

  wave form/shape: high plunging waves with a short wavelength

  breaking characteristsics: weak swash, strong backwash

  net effect on beach: beach loss

  beach profile: usually associated with steeper beach profile although over time they will flatten the beach

  wavelength: generally less than 20m

  wave frequency: (high) 10-12 per minute

  wave period: (low) one every 5-6 seconds

  also known as: storm or plunging waves