Coasts-waves Flashcards

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1
Q

Are Rip currents strong or week?

A

Strong currents moving away from the coast line.

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2
Q

When do rip currents occur?

A

They occur when seawater is piled up along the coastline by incoming waves.

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3
Q

The current may run in which direction?

A

Parallel to the coast before flowing through the breaker zone- possibly at the headland or where the coast changes direction.

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4
Q

Longshore currents occur when?

A

They occur as most waves do not hit the coastline ‘head on’ but approach at a angle to the shoreline.

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5
Q

When longshore currents hit the coastline, what do they produce?

A

Generates a flow of water running parallel to the shoreline.

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6
Q

Where does the water then move to?

A

The water moves along the surf zone, also transports sediment parallel to the shoreline.

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7
Q

What is the wave height?

A

The height between a wave crest and neighbouring trough.

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8
Q

What is the wavelength or amplitude?

A

The distance between successive crests.

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9
Q

What is the wave frequency ?

A

The time for one wave to travel the distance of one wavelength, or the time between one crest and the following crest passing a fixed point.

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10
Q

What height do constructive waves have?

A

Low height

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11
Q

What wavelength do constructive waves have?

A

Long wavelength

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12
Q

What frequency does constructive waves have?

A

Low frequency

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13
Q

What happens to swash when constructive waves occur?

A

Swaths quickly loses volume and energy as water percolates through the beach material.

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14
Q

What wave height does destructive waves have?

A

High wave height

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15
Q

What frequency does destructive waves have ?

A

Steep form& high frequency

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16
Q

What happens to destructive waves as they approach the beach?

A

Rapidly steepen, when break they plunge down.

17
Q

What type of backwash do destructive waves have?

A

Powerful backwash

18
Q

What effect does destructive waves have on material?

A

Very little material moved up the beach.

19
Q

How do upwelling currents begin ?

A

Movement of cold water from deep in the ocean towards the surface.

20
Q

What does the more dense cold water do in a upwelling current?

A

The more dense cold water replaces the warmer surface water.

21
Q

What does the replacement of cold water do?

A

Creates nutrient rich cold ocean currents.

22
Q

What do the currents then form?

A

They form part of the pattern of global ocean circulation currents.