Sources Of Energy Wind/wave/currents/tide

Question 1

Why is wind so significant?

Answer 1

It is a primary source of energy for other processes, important agent for erosion and transport itself.

Question 2

Higher / uninterrupted wind will create what kind of waves ?

Answer 2

Higher energy waves

Destructive

Question 3

Prevailing wind direction

Answer 3

Wind reaching coast from one direction.

Which is important as this controls direction that waves approach coastline and also direction of transport of material in coastal zone.

Question 4

Fetch

Answer 4

Refers to the distance of pen water which wind blows uninterrupted by land obstacles.

Length of fetch helps determine magnitude and energy of waves

Question 5

How does wind create waves?

Answer 5

Waves are created by transfer of energy from the wind blowing over the sea surface “frictional drag”

Energy acquired by waves depends upon strength of wind and length / time it’s blowing and the fetch.

Question 6

How does wind act as an agent of erosion ?

Answer 6

Pick up and remove sediment from coast and use this to further erode other features.

Abrasion is the most common type of wind erosion - wind carries material wearing away landscape

Question 7

Why are waves significant?

Answer 7

They shape the coastline

Question 8

WAve height

Answer 8

Difference between wave crest and neighbour trough

Question 9

Wave length

Answer 9

Distance been 2 successive crests

Question 10

Wave frequency

Answer 10

Time for 1 wave to travel the distance if one wave length

Question 11

What happens when waves approach shallow water ?

Answer 11

Friction with seabed increases and the base of the wave begins to slow down.

Increases height / steepness of wave until upper part plunges forward and wave breaks Onto shore

Rushes up beach as swash and any water running back down beach is backwash.

Question 12

Characteristics of constructive waves

Answer 12

Low wave height

Long wavelength -100m

Low frequency 6-8 per min

As approach beach the wave front steepens slowly giving gentle spill.

Swash is larger than backwash as swash loses volume / energy percolating into beach material.

Weak backwash means not much material is pulled back.

Question 13

Constructive waves and beach material

Answer 13

Strong swash and weak back wash means material is slowly but constant moves up beach leading to formation of berms

Built beach up

Question 14

Characteristics of destructive waves

Answer 14

High wave height

Steep form / beach profile

High frequency 10-14 per min

As they approach beach they rapidly steepen and break plunging down creating power backwash as there is little swash

Question 15

Destructive waves as material

Answer 15

Very little material moved up beach as backwash pulls material down.

Question 16

Storm beach

Answer 16

When shingle goes towards rear of the beach forming large ridges

Question 17

Cycle of waves

Answer 17

Constructive waves build up beach and result in steeper beach profile.

This encourages destructive waves to occur as they’re associated with more steeper beach profile.

With time destructive waves move material back towards the sea reducing the beach angle and encouraging more constructive waves.

Negative feedback - maintains equilibrium

Question 18

What happens when waves approach an irregular shaped coastline.

Answer 18

They become refracted and increasingly parallel to coast.

When they meet shallow water around headland waves increase in height as speed decreases.
Wave in deep water moves forward faster, causing wave to bend.

Energy concentrated on headland causing greater erosion.

Low energy waves concentrated in bay resulting in sheltered area and deposition occurring.

May be slight local rise in sea level due to piling of waves against headland which results in longshore currents from headland - moving material to bay leading to build up of beaches.

Question 19

Define current

Answer 19

Permanent / seasonal movement of surface water in seas and oceans

Longshore current

RIP current

Upwelling

Question 20

Longshore currents

Answer 20

Waves don’t hit coastline heady on but approach at an angle to shoreline

Generates flow of water running parallel to shoreline.

Transports sediment parallel to shoreline

Question 21

RIP currents

Answer 21

Strong currents moving away from
Shoreline

Pile up of incoming waves.

Hazardous to boats/ swimmers

Question 22

Upwelling

Answer 22

Movement of cold water from deep in ocean towards surface

Dense cold water replaces warmer surface water and creates nutrient cold rich currents

Question 23

Define tides

Answer 23

Periodic rise and fall in the level of the sea by gravitational pull of the sun and moon

Question 24

Spring tide

Answer 24

Moon orbits earth

Twice in a lunar month when moon/ earth / sun are in straight line the tide raising force is strongest.

Highest month tidal range / SPRING TIDE.

Question 25

Neap tide

Answer 25

Twice a month
The moon and sun positioned at 90 degrees to each other in relation to earth.

Lowest monthly tidal range /NEAP TIDE.

High/ low tides are 10-30% lower than average

Question 26

Who has greater influence on tide ?

Answer 26

Moon as it’s nearer

Moon pulls water towards it.

Question 27

How is tide different in individual locations ?

Answer 27

Morphology of sea bee

Proximity of land masses

Spinning force of earth

Tidal range

Question 28

Tidal range

Answer 28

Different in height of sea water at high and low tide.

Question 29

what do tidal ranges determine?

Answer 29

Upper and lower limits of erosion / deposition.

And amount of time each day that the littoral zone is exposed and open to sub aerial weathering

Question 30

Example low tidal ranges

Answer 30

Mediterranean Sea

Question 31

Example of high tidal range

Answer 31

British isles

Erosional land scales like wave cut platforms

Question 32

Tidal/ storm surge

Answer 32

Meteorological conditions give rise to sting winds producing higher water levels than those at high tide

Eg North Sea

Question 33

High energy coast

Answer 33

strong / steady / prevailing winds create high energy waves

Erosion exceeds deposits

Headlands / cliff

N. America
N. Cornish coast

Question 34

Low energy coast

Answer 34

Wave energy is low and not as strong winds.

Deposition exceeds Erosion

Beaches / spits

Estuaries / inlets

The Baltic Sea