Sources Of Energy Flashcards
What are the energy sources (4)
Wind
Waves
Tides
Currents
Where does wind move (2)
Air moves from areas of high atmospheric pressure to areas of low atmospheric pressure
Larger pressure gradient between two places = stronger wind
Waves in UK specifically (2+)
The prevailing (most usual) wind direction is from the south-west
Before reaching our coast = winds blown over the broad expanse of the Atlantic Ocean
What is the fetch
The distance wind travels over open water
What affects wave energy (3+)
Fetch
Strength of wind
Duration of wind
What is wind an agents of (2+)
Erosion = pick up and remove sediment from the coast and use it to erode other features
Moving sediment = it can pick up and move material
What agent does waves act as
Shaping the shoreline
Constructive waves what (5+)
Swash pushes more material from offshore up the beach than the backwash removes
Long wavelength
Low in height
Low in frequency
Deposition
Constructive wave beach look like (2+)
Gentle beach profile
Over time they will build up the beach and make it steeper
Destructive waves (5+)
Steep in height
Short in frequency
High in energy
Swash is short-lived and the backwash is forceful and takes material down the beach
Net effect = removal of beach material along the shoreline
Beaches and waves negative feedback (4+)
Constructive waves build up a beach
Beach profile steepens which can encourages destructive waves = remove material from the beach and deposit it offshore
Result = beach profile becoming less steep again = encouraging constructive to form
This will continue until a state of dynamic equilibrium is reached
Waves around a headland (4)
Tend to ‘bend’ and have a higher frequency
Wave height steepness = erode
Waves approaching the headland meet shallower water first = friction with the sea floor
Slows headland-approaching waves and causes their frequency to increase
Waves around a bay (3+)
Waves spread out and become less frequent
Leads to a reduction in wave energy
Deposition
What is ave refraction (2+)
When waves approach a coastline that is indented they are refracted
Become increasingly parallel to the coastline
Overall impact of wave refraction (2)
Wave energy becomes concentrated on the headland
Presence of erosive features at headlands and deposition features in bays
Theory of wave refraction (2)
Continued erosion of the headland and deposition in the bays
State of equilibrium where the shape of the coastline remains static
What does the term current refer to
The permanent or seasonal movement of surface water in the seas and oceans
Type of currents (3)
Longshore
Rip
Upwelling
What is a longshore current (3)
Occur because most waves approach the coastline at an angle
Result is a flow of water running parallel to the shoreline
Moves water and transports sediment parallel to the shoreline
What is a rip current (3)
Strong localised underwater currents
Move water away from the shoreline
The fast-flowing offshore surge of water can be hazardous to swimmers
How does a rip current form (2++)
When a series of plunging waves cause a temporary build-up of water at the top of the beach
Met with resistance from the breaking waves - the backwash is forced just below the surface following troughs in the beach profile
What is an upwelling (3+)
Movement of cold water from deep in the ocean towards the surface
The dense cold water replaces warmer surface water = nutrient rich cold ocean currents
Form part of the pattern of global ocean circulation current
What creates tides (2+)
Rise and fall in sea levels
Due to gravitational force of the moon, the sun and the rotation of the earth
What does moon do to form tides (3+)
Pulls water towards it = high tide
There is a compensatory bulge on the opposite side of the Earth
In areas of the world between the two bulges = the tide is at its lowest
What is tidal range
The relative difference in height between high and low tides
What do tidal ranges determine
The upper and lower limits of erosion and deposition
What is spring tide (3+)
Twice a month = the sun, the moon and earth form a line
Tidal force is at its maximum
Total range is at its highest
What is the neap tide (3)
Sun and moon at 90°
Solar tidal force cancels the moon gravitational force
Tidal range + force at their minimum
Features of a high energy coastline (4)
Strong waves
Strong prevailing winds
Long fetch
Rate of erosion bigger than deposition
Example of high energy coast in UK (2)
Cornwall
North-west Scotland
Low energy coastline features (3)
Waves are less powerful
Rate of deposition is greater than erosion
Wave energy is low
Example of low energy coast in UK
Lincolnshire
