Coats 1

Systems, the Atmosphere, features of coasts and how coasts are energised.

What is a system?

System is an assemblage of interrelated components that work together through inputs, outputs, stores, and flows.

What are the 3 types of system?

Closed, Open and Isolated.

What is a closed system?

A system that has no inputs or outputs, but which cycles energy or resources around a closed loop.

No exchange of matter or energy occurs.

What is an open system?

A system that has both inputs and outputs of energy and other material (water!) and which involves a flow or exchange of material.

What is an isolated system?

 A system that has no interactions beyond its boundary layer - that is that the system is so far removed from other systems, that it does not interact with them - a laboratory experiment is a good example of this.

When does dynamic equilibrium occur?

If inputs and outputs are equal.

What are earth’s 4 subsystems?

Atmosphere, lithosphere, hydrosphere and biosphere.

What does the atmosphere consist of?

All gases in the air.

A mixture of nitrogen, oxygen and other gases which surround earth.

What does the lithosphere consist of?

The crust and uppermost part of the mantle; this constitutes the hard and rigid outer layer of the Earth.

It is this layer which is split into tectonic plates. (ALSO called geosphere)

What does the hydrosphere consist of?

A discontinuous layer of water at or near the Earth's surface.

It includes all liquid and frozen surface waters, groundwater held in soil and rock and atmospheric water vapour.

What does the biosphere consist of?

The sum of all living matter. Includes many different biomes such as deserts, forests and wet lands.

What are the subsections of the atmosphere?

Troposphere, Stratosphere, Mesosphere, Thermosphere, Exosphere and Geosphere

Describe the Troposphere.

The lowest lane of the atmosphere (closest to earth).

Contains 80% of the air in the atmosphere, where all weather occurs; includes the global atmospheric circulation system.

Describe the Stratosphere.

Above the Troposphere. Absorbs UV Rays (crucial for shielding life) as contains the ozone layer.

Contains less clouds and less air.

Describe the Mesosphere.

Coldest layer of the atmosphere, almost no breathable air.

Describe the Thermosphere.

Temperature increases sharply, reaching 1,500°C+ due to solar radiation absorption.

Contains the ionosphere, enabling radio communication and auroras.

Space stations orbit here.

Describe the Exosphere.

Highest you can go without leaving earth. Extremely thin; merges into space.

Contains very sparse particles (hydrogen, helium)

Describe the Geosphere.

Solid earth, all rocks and mineral on earth including volcanoes.

What does a coastal landscape shape the interactions of?

1. The nature and structure of the rock or materials constituting the coastline

2. The climate component determining the range and intensity of weathering processes

3. The marine processes operating to produce features of erosion and deposition

4. The input of energy and sediment into the coastal zone.

5. The amount of time that has passed to develop or interrupt processes operating to produce features

What is a coastal landscape?

A section of coastline that has a range of coastal features or landforms, some erosional, some depositional.

What may different coastal landscapes represent?

1. Metastable coastal environment: where processes (and thus features) change rapidly such as with tectonic uplift, leaving relict features apparent.

2. Stable equilibrium occurs on a coastal environment with little long term change and time for the full evolution of coastal landforms.

3. Historical coastal environment: evidence of ancient processes, sea levels, features with more recent features superimposed as a result of different conditions operating at time up to the present.

What is a Cliff face?

A steep rock slope formed by marine erosion at the coast.

What is a storm beach?

A ridge of large pebbles or shingle deposited above the normal high tide line during storms.

What is a berm?

A ridge or terrace of deposited sediment formed by constructive waves at different tide levels.

What is a beach face?

The sloping section of beach between the berm and the swash zone where waves actively move sediment.

What is a beach cusp?

Small crescent-shaped ridges and hollows formed by wave swash and backwash along the shoreline.

What are ripples?

Small ridges in sand created by wave or current action.

What are runnels?

A shallow trough or channel that holds water between ridges on the beach.

What is a ridge?

An elongated accumulation of sand or shingle created by wave deposition.

What is a breached ridge?

A ridge that has been cut through by water flowing seawards.

What is the breaker zone?

The area offshore where waves become unstable and break due to decreasing water depth.

What is backshore?

The upper beach, usually only affected by waves during storms or exceptionally high tides.

What is foreshore?

The section of beach between high and low tide marks that is regularly covered and exposed by tides.

What is nearshore?

The zone extending offshore from the low tide mark where waves begin to interact with the seabed.

What is swash?

Water moving up the beach as a wave breaks in the direction of the prevailing wind.

What is backwash?

Water flowing back down the beach under gravity.

What is Longshore drift?

The transportation of sediment along the coast by waves approaching at an angle.

What is wind?

Wind is the movement of air from areas of high pressure to low pressure. It is the ultimate source of energy for most coastal processes.

How does wind influence the coast?

1. Generates waves through friction between air and the sea surface.

2. Stronger winds transfer more energy to the water.

3. Wind strength, duration and fetch determine wave energy.

What is fetch?

The uninterrupted distance over water that wind blows.

What are waves?

Oscillations that transfer energy across the water surface.

What does wave energy depend on?

Wave height (amplitude) = height from trough to crest.

Wavelength = distance between two crests.

Wave frequency = number of waves passing a point per minute.

Greater height and frequency = greater energy.

What are the characteristics of constructive waves?

Low wave height.

Long wavelength.

Low frequency (6-8 waves per minute).

Strong swash, weak backwash.

How do constructive waves impact the coast?

Deposits sediment as swash exceeds backwash.

Builds beaches.

Associated with low-energy coastlines.

What are the characteristics of destructive waves?

High wave height.

Short wavelength.

High frequency (10-14 waves per minute).

Weak swash, strong backwash.

How do destructive waves impact coasts?

Erode beaches and cliffs as backwash exceeds swash.

Remove sediment offshore.

Associated with high-energy coastlines.

What is wave refraction?

The bending of wave crests as they approach an irregular coastline.

Waves enter shallow water.

Parts of the wave touching shallow water slow first due to friction.

Other parts continue moving faster.

Wave crests bend around headlands.

How does wave refraction influence headlands?

• Wave energy becomes concentrated.

• Increased hydraulic action and abrasion.

• Enhanced erosion.

How does wave refraction influence bays?

• Wave energy becomes dispersed.

• Reduced erosion.

• Increased deposition.

Describe the process of longshore drift.

1. Waves approach at an angle determined by prevailing winds.

2. Swash moves sediment up the beach at the same angle.

3. Backwash returns under gravity at 90° to the shoreline.

4. Sediment moves along the coast in a zig-zag pattern.

What is the importance of Longshore Drift?

Main method of sediment transport along coastlines.

Forms spits, bars and tombolos.

What are Rip Currents?

Narrow, fast-moving channels of water flowing seaward from the beach.

How are Rip Currents formed?

Water accumulates near shore due to incoming waves and returns seawards through concentrated channels.

Why are rip currents important

Remove sediment from beaches.

Transport material offshore.

Can increase coastal erosion.

What is upwelling?

The vertical movement of deep, cold, nutrient-rich water to the surface.

What is upwelling caused by?

Offshore winds move surface water away.

Deep water rises to replace it.

Why is upwelling important?

Creates highly productive marine ecosystems.

Supports major fisheries.

Influences coastal climates.

What are tides?

The periodic rise and fall of sea level caused mainly by the gravitational pull of the Moon and, to a lesser extent, the Sun.

When do Spring tides occur?

Sun, Moon and Earth are aligned.

During new moon and full moon.

What are the characteristics of spring tides?

Greatest tidal range.

Highest high tides.

Lowest low tides.

What are the impacts of spring tides?

Increased coastal flooding potential.

Greater erosion and sediment movement.

When do neap tides occur?

Sun and Moon are at right angles to Earth.

During first and third quarter moons.

What are the characteristics and impact of neap tides?

Smallest tidal range.

Lower high tides.

Higher low tides.

Impact: Reduced tidal energy

What are tidal surges?

A temporary and abnormal rise in sea level above the predicted astronomical tide.

What are causes of tidal surges?

Low atmospheric pressure.

Strong onshore winds.

Storm systems (especially tropical cyclones and intense depressions).

What are the impacts of tidal surges?

Coastal flooding.

Increased erosion.

Saltwater intrusion.

Damage to infrastructure.

Describe what a high energy coast may experience.

Exposed to strong winds

Long fetch

Dominated by destructive waves

Erosion exceeds deposition

Steep rocky cliffs

High wave frequency

Describe what a low energy coast may experience.

Sheltered from prevailing winds

Short fetch

Dominated by constructive

Deposition exceeds erosion

Wide sandy beaches

Low wave frequency

Which landforms often occur on high energy coasts?

1. Cliffs

2. Wave-cut platforms

3. Caves

4. Arches

5. Stacks

6. Stumps

Which landforms often occur on low energy coasts?

1. Beaches

2. Spits

3. Bars

4. Tombolos

5. Mudflats

6. Salt marshes

What is a metastable coastal environment?

Where processes (and thus features) change rapidly such as with tectonic uplift, leaving relict features apparent.

What is stable equilibrium?

Occurs on a coastal environment with little long term change and time for the full evolution of coastal landforms.

What is a historical coastal environment?

Evidence of ancient processes, sea levels, features with more recent features superimposed as a result of different conditions operating at time up to the present.