3.1.3.2 Sources of energy Flashcards
What are the 4 shores?
backshore, foreshore, nearshore, offshore
Explain how winds are formed and how a strength of a wind can be effected by its formation?
Wind is created when air moves from areas of high pressure to areas of low pressure.
When the solar radiation heats air, it rises and creates areas of lower pressure. Surrounding cooler (more dense) air which is under higher pressure then tries to fill the space vacated by the rising warmer air.
The greater the difference in pressure the greater the amount or air transfer or wind.
Explain how the sun is the primary source of energy in wave formation.
The solar radiation warms up the hair which makes the air become less dense and cause it to rise resulting in low pressure. High pressure air will rush in to fill the void left by low pressure and create wind. The wind will create friction on the ocean surface.
How are waves formed?
1) Wind creates friction on the surface of the water causing a wave
2) within the wave each particle moves in a circular motion
3)When the wave moves to the shallower area the motion is distorted causing it to move forward.,
4)From here the wave breaks and the energy causes it to topple forward.
5) Water rushes up to the beach. This is called swash.
6) Then due to the gradient of the beach the water moves back due to gravity and this is called backwash.
What shape does energy in waves take in SHALLOW water?
Elliptical (Oval)
Explain what causes a wave to break as it reaches the shoreline
Wave is slowed by friction with the seabed causing an elliptical shape. This causes the crest of the wave to rise, until it becomes ‘top heavy’ and crashes down. (This happens when the ratio of wave height to length reaches 1:7)
What is crest, wavelength and trough?
Crest - highest point of each wave
Trough is lowest point of a wave
Wave length - distance between each wave.
3 factors that effect wave energy?
velocity - speed of the wind
duration - period of time which wind blew
fetch - distance which over wind blew
Do waves become faster deeper the ocean?
Yes- less friction due to greater distance
How will increased velocity affect a wave energy graph
Produce higher frequency waves
constructive vs destructive
Constructive:
1)Beach gain of sediment: Stronger swash on break and weaker backwash
2)Usually associated with a gentle beach profile—although, over time, they will build up the beach and make it steeper.
3)Low surging wave form with long wave length
4)waves do not reach the base of the cliffs not enough wave energy
5) Ridge of sediment(berm) deposited by the wave
destructive
1)Upper parts of cliffs attacked by sea spray
2)Waves reach the base of cliffs
3)Usually associated with a steeper beach profile—although, over time, they will flatten the beach.
4)High, plunging wave form with a short wavelength.
5)Weak swash on break, strong backwash.
6)Beach Loss of sediment
How will increased duration of wind affect wave energy graph
increases wave height
Explain how a beach could be subjected to alternating cycles of constructive and destructive waves using a systems approach
Most beaches are subject to an alternating cycle of constructive and destructive waves. Constructive waves build up the beach resulting in a steeper beach profile. This encourages waves to become more destructive (as destructive waves are associated with steeper profiles). With time, though, destructive waves move material back towards the sea, reducing the beach angle and encouraging more constructive waves. So the pattern repeats itself. This is another example of negative feedback that should maintain the state of dynamic equilibrium, but this is often impossible as other factors, such as wind strength and direction, are not constant.
