coastal systems -sources of energy at the coast (wind and waves)

Question 1

where does energy at the sea come from?

Answer 1

.waves -occasionally can be due to tectonic activity but mainly are due to wind

Question 2

how is wind created?

Answer 2

.when air moves from high pressure (cool air) to low pressure (warm air that rises)

Question 3

what are process caused by wind referred to as?

Answer 3

.aeolian processes

Question 4

what kind of wind do coasts have?

Answer 4

.prevailing wind

Question 5

what does the prevailing wind direction control?

Answer 5

.controls the direction at which waves approach the coastline and the direction of transportation

Question 6

what does the role of wind play a key part in?

Answer 6

.wave formation –frictional drag of the wind at the surface
.transportation -move sediment along the coast, inland and beyond the tidal zone
.erosion – wind can pick up sediment from the coast and hurl it against features on the coast to erode

Question 7

how does wind create waves?

Answer 7

.as wind moves across the surface of water it causes friction and changes in pressure
.this pulls the crest of the wave up and pushes the trough of the wave down -this makes the water begin to roll in a circular orbit which creates a wave as it travels along

Question 8

what is the size and energy of waves dependent on?

Answer 8

.strength of the wind (stronger the wind, the higher the wave energy)
.how long the wind has been blowing for (longer duration, higher wave energy)
.distance of ocean the wind blows over -fetch (the longer the fetch, the higher the wave energy)

Question 9

what are the 2 types of waves?

Answer 9

.destructive
.constructive

Question 10

what are the features of a destructive wave?

Answer 10

.high wave height
.short wave length
.break in deep water
.erode the beach because they have a weak swash and strong backwash
.high energy

Question 11

what are the features of a construe wave?

Answer 11

.low wave height
.long wave length
.break in shallow water
.build up the beach because they have a strong swash and weak backwash
.low energy

Question 12

what is wave refraction?

Answer 12

.when waves approach a coastline that is indented, they are refracted and become increasingly
parallel to the coastline eg -around a headland, waves tend to bend

Question 13

what is the effect of wave refraction?

Answer 13

.wave energy becomes concentrated on the headland as the waves meet shallower water so waves get higher and become destructive -accounts for the presence of erosive features at headlands (cliffs, stacks)
.deposition features in bays as waves stay in the deeper water so waves remain lower and are constructive