Sources of energy in coasts Flashcards
(24 cards)
What are the 4 sources of energy in coasts?
Wind, wave, currents and tides
If there is low wind pressure, what will the waves be like?
Big waves as air is lifting
What does prevailing wind often cause?
High energy waves
Name 3 ways that wind is important in the coastal systems
- wind can erode coastline through abrasion as it picks material up and transports it to wear away coastline.
- wind forms waves by transferring energy to surface water creating frictional drag.
- prevailing winds often bring high energy waves
What are the 3 factors that affect the size and strength of waves?
- strength of wind
- fetch ( the distance of open water which wind blows uninterrupted by land obstacles)
- duration of wind - longer it blows the more powerful the waves.
What is the fetch?
The distance of open water which wind blows uninterrupted by land obstacles.
The longer the fetch…
The stronger the wave
What are the 2 types of waves?
Constructive and destructive
Name 3 of characteristics of constructive waves
- strong swash, weak backwash
- builds up beach profile
- forms when beach gradient is gentle
Name 3 characteristics of destructive waves
- strong backwash, weak swash
- high waves with short wave length
- erodes coastline and forms on steep gradient beach
What is the alternating cycle, when it comes to waves?
Constructive waves build up the beach profile which then encourages destructive waves as a steep beach gradient formed. Creating a negative feedback loop
What is wave refraction?
the process by which waves turn and lose energy around a headland on irregular coastlines.
What happens in wave refraction?
The waves are refracted so that their energy is concentrated into the headlands and the rest of the energy is gently dissipated at the bays. Meaning that the headland is eroded at faster rate than the rest of coastline.
Why is wave refraction an example of negative feedback?
The headland will erode back to become level with the rest of the coastline and then be even again.
What is the name given to the highest monthly tide?
Spring tide
Describe the location of the sun and moon during a spring tide.
The sun and moon are in line with the earth
What is the name given to the lowest monthly tide?
Neap tide
Describe the location of the sun and moon during a neap tide
Sun and moon are at right angle to each other.
What are tides?
The periodic rise and fall of the sea caused by gravitational pull of the sun and moon.
Name 2 ways that the tides are important in the coastal system
- significant flow of water can generate strong currents which influence the direction and scale of coastal sediment.
- Larger the tidal range, the more extensive the intertidal zone which is subject to erosion.
How many times a month do spring tides occur?
twice a month
How many times a month do neap tides occur?
twice a month
What are rip currents?
powerful, localised, underwater currents - consistent swash, swash, swash so not enough time to backwash.
Backwash forced under surface due to resistance from breaking waves.
What is upwelling?
When winds push the surface water away from the shore and the deeper water rises to fill the gap.
