Coasts- Lesson 2 Waves

Question 1

What is a crest?

Answer 1

Highest point of the wave

Question 2

What is a trough?

Answer 2

Lowest point of the wave

Question 3

What is backwash?

Answer 3

Any water returning down to the sea

Question 4

What is wave height?

Answer 4

The distance between the crest and the trough, rarely exceeds 6 metres unless storm conditions

Question 5

What is the swell?

Answer 5

Waves of low height, gentle steepness, long wave length and period

Question 6

What is wave velocity?

Answer 6

Is the speed of movement of a crest in a given period of time

Question 7

What is wave steepness?

Answer 7

Is the ratio of the wave height to wave length

Question 8

What is the wave period?

Answer 8

Time taken for a wave to travel through one wave length

Question 9

What is the plunge line?

Answer 9

The point where the wave breaks

Question 10

What is the swash?

Answer 10

The body of foaming water rushing up the beach

Question 11

What is the wave length?

Answer 11

The distance between two successive crests

Question 12

Waves are the…to the coastal system and created by…

Answer 12

• main input of energy to a coastal system

- created by energy transfer from the wind

Question 13

The wave size increases as…

Answer 13

The strength of wind increases

Question 14

When the wave approaches the shore the speed of water at the top of the wave…

Answer 14

Exceeds that of the rest of the wave so it toppled over and breaks due to friction

Question 15

The part of the wave toppling over is…

Answer 15

Twice as fast as the rest of the wave

Question 16

The energy obtained by waves depends on…

Answer 16

• wind velocity
• length of the fetch
• period of time during which the wind has blown
• depth of water

Question 17

What is the fetch?

Answer 17

Maximum distance of open water over which wind can blow. Places of greatest fetch receive highest energy waves

Question 18

How does water depth effect waves reaching shore?

Answer 18

Shallow water offshore reduces the energy reaching the coast

Question 19

Waves that travel short distances are a result of…and are known as…?

Answer 19

Local winds and known as Sea waves

Question 20

Waves that travel longer distances are formed by… and known as…?

Answer 20

Distant storms and known as swell waves

Question 21

What’s is Britain mainly affected by and where?

Answer 21

Britain is mainly affected by sea waves but swell waves occur in Cornwall as the coast faces open ocean

Question 22

What is a constructive wave?

Answer 22

• created in calm weather conditions
• depositional wave
• powerful swash weak backwash
• common when long fetch exists
• long, low gradient, may not break
• 6-9 per minute frequency

Question 23

What are destructive waves?

Answer 23

• created in storm, winter conditions
• less swash greater backwash
• destroy beach, erosive
• tall so create steep narrow beaches
• high in proportion to length which is short
• frequency is 12-15 per minute

Question 24

What is wave refraction?

Answer 24

• occurs along a discordant coastline
• headland is hard more resistant rock and bay is soft less resistant rock
• when waves approach the coastline that isn’t a regular shape they are refracted and become increasingly parallel to the coastline
• as waves reach the shore the drag in shallower water which meets the headland
• this causes the waves to become higher and steeper with a shorter wave length
• the part of the wave in deeper water moves forward faster causing the wave to bend
• the overall effect is that the wave energy becomes concentrated at the headland causing greater erosion there (erosion process)
• low energy waves spill into the bay causing beach deposition