Chapter 13Chapter 13

Ocean MotionOcean Motion

What is a wave?What is a wave?

The movement of energy through The movement of energy through a body of water.a body of water.

Most waves form when wind blows Most waves form when wind blows across the surface of the ocean across the surface of the ocean water and energy is transferred water and energy is transferred from air to water.from air to water.

Wave SizeWave Size

The size of the wave depends:The size of the wave depends: 1. strength of the wind 1. strength of the wind 2. length of time wind blows 2. length of time wind blows 3. distance the wave travels.3. distance the wave travels. Wave Energy: as a wave moves Wave Energy: as a wave moves

across the water, the water does across the water, the water does not move positions.not move positions.

Wave motionWave motion

Waves move in a circular pattern. Waves move in a circular pattern. They spring forward, then down, They spring forward, then down, then up to original position.then up to original position.

Wave depth: most waves are not Wave depth: most waves are not very deep in the ocean. If you were very deep in the ocean. If you were in a sub, you would never feel the in a sub, you would never feel the size of waves.size of waves.

Wave characteristicsWave characteristics

Highest point: crestHighest point: crest Lowest point: troughLowest point: trough Wavelength: Distance between 2 crests Wavelength: Distance between 2 crests

or 2 troughsor 2 troughs Frequency: the number of waves that Frequency: the number of waves that

pass a certain point in a certain amount pass a certain point in a certain amount of timeof time

Wave height: distance between crest and Wave height: distance between crest and trough.trough.

Diagram of a WaveDiagram of a Wave

How waves change at How waves change at shore!shore!

White capped waves that crash in White capped waves that crash in to shore are called to shore are called breakersbreakers. They . They form when the bottom of the wave form when the bottom of the wave begins to drag in shallow water. begins to drag in shallow water. The top of the wave continues on… The top of the wave continues on… and the wave’s circular motion fall and the wave’s circular motion fall apart or breaks!apart or breaks!

A day at the BeachA day at the Beach

TsunamisTsunamis

Type of wave caused by Type of wave caused by earthquake energy.earthquake energy.

Most common in Pacific Ocean Most common in Pacific Ocean around Alaska, Hawaii, Japan, around Alaska, Hawaii, Japan, Southeast Asia.Southeast Asia.

How waves affect the How waves affect the shoreshore

Longshore drift: as waves come Longshore drift: as waves come into shore, water washes up the into shore, water washes up the beach at an angle, carrying sand beach at an angle, carrying sand grains. The water and the sand grains. The water and the sand then run straight back down the then run straight back down the beach which make sandbars.beach which make sandbars.

Rip currentsRip currents

As a sandbar grows, it can trap As a sandbar grows, it can trap water as it flows from shore. As is water as it flows from shore. As is goes back to the ocean it forms a goes back to the ocean it forms a rip current which is a rush of water rip current which is a rush of water that flows rapidly back to sea that flows rapidly back to sea through a narrow opening. These through a narrow opening. These are very dangerous to swimmers.are very dangerous to swimmers.

Rip CurrentsRip Currents

Waves and Beach ErosionWaves and Beach Erosion

Beaches never remain the same Beaches never remain the same because sand is constantly being because sand is constantly being eroded in some places and built up eroded in some places and built up in others.in others.

Sand is formed over thousands of Sand is formed over thousands of years of waves hitting rocks and years of waves hitting rocks and cliffs.cliffs.

Barrier BeachesBarrier Beaches

A natural landform that protects A natural landform that protects shorelines from beach wave action.shorelines from beach wave action.

These beaches are separated by These beaches are separated by the mainland by a lagoon.the mainland by a lagoon.

Ex: Cape Cod, Georgia and Ex: Cape Cod, Georgia and Carolina coasts, MiamiCarolina coasts, Miami

Sand DunesSand Dunes

Hills of windblown sand that make Hills of windblown sand that make beaches more stable and protect beaches more stable and protect the shore from erosion.the shore from erosion.

Groins: a wall that is built by Groins: a wall that is built by people of rocks or concrete to try people of rocks or concrete to try to protect beaches and homes to protect beaches and homes from erosion.from erosion.

13.3 Ocean Water 13.3 Ocean Water ChemistryChemistry

Earth’s surface is 70% oceans.Earth’s surface is 70% oceans. The oceans are salt water- because The oceans are salt water- because

salts of sodium chloride, sulfur, salts of sodium chloride, sulfur, magnesium, calcium and potassium magnesium, calcium and potassium are dissolved in the ocean water.are dissolved in the ocean water.

The salts come from dissolved The salts come from dissolved minerals from rocks that were minerals from rocks that were transported to the ocean or from transported to the ocean or from volcanic activity.volcanic activity.

SalinitySalinity

In seawater the most abundant elements In seawater the most abundant elements are sodium and chlorine. These two are sodium and chlorine. These two elements form a compound called halite.elements form a compound called halite.

Halite is the salt used to season food.Halite is the salt used to season food. Salinity is the measure of the amount of Salinity is the measure of the amount of

salt in seawater. It is measured in grams salt in seawater. It is measured in grams of salt per kilogram. One kilogram of of salt per kilogram. One kilogram of water usually holds 35g of salts. That is water usually holds 35g of salts. That is 35 parts per thousand.35 parts per thousand.

Salinity Lows and HighsSalinity Lows and Highs

Salinity is lower near the surface Salinity is lower near the surface where rain and melting ice add fresh where rain and melting ice add fresh water to the ocean.water to the ocean.

Salinity is higher in hot dry climates Salinity is higher in hot dry climates where there is a lot of evaporation where there is a lot of evaporation and near the poles where much of and near the poles where much of water is frozen as ice and salt water is frozen as ice and salt remains in liquid water. This make remains in liquid water. This make ocean water dense.ocean water dense.

Temp of Ocean WaterTemp of Ocean Water

Temperatures at the surface of Temperatures at the surface of ocean water vary with location and ocean water vary with location and seasons. Warmest near equator and seasons. Warmest near equator and coldest at poles.coldest at poles.

Temperature decreases as you go Temperature decreases as you go down in the waterdown in the water

At 1 km down it is about 4 Deg CAt 1 km down it is about 4 Deg C Below that it remains about 3.5 deg Below that it remains about 3.5 deg

CC

Pressure of ocean waterPressure of ocean water

Pressure increases continuously as Pressure increases continuously as you go further downyou go further down

A diver can only go down about 40 A diver can only go down about 40 meters safelymeters safely

After that depth a submersible is After that depth a submersible is needed.needed.

13.4 Ocean Currents13.4 Ocean Currents

Surface CurrentsSurface Currents

Surface currents move water Surface currents move water horizontally-parallel to the Earth’s horizontally-parallel to the Earth’s surface.surface.

Surface currents are powered by Surface currents are powered by the wind. Friction between the the wind. Friction between the wind and water cause the water to wind and water cause the water to move, driving the ocean water in move, driving the ocean water in huge circular patterns.huge circular patterns.

Surface CurrentsSurface Currents

Surface currents move only the upper few Surface currents move only the upper few hundred meter of water, though some are hundred meter of water, though some are as deep as 1000mas deep as 1000m

Surface currents carry seeds, plants, and Surface currents carry seeds, plants, and messages in bottles.messages in bottles.

Ocean CurrentsOcean Currents

Famous Surface CurrentsFamous Surface Currents

Antarctic Antarctic Circumpolar Circumpolar Current-Current-

Strongest surface Strongest surface current and the current and the only one that only one that circles the Earth.circles the Earth.

The Gulf StreamThe Gulf Stream Sailors back in Sailors back in

colonial times used colonial times used the Gulf Stream to the Gulf Stream to sail from North sail from North America to America to England.England.

It is 100 km wide It is 100 km wide and allowed sailors and allowed sailors to use the wind to to use the wind to get across the get across the ocean quickly.ocean quickly.

Sneakers Galore!Sneakers Galore!

In 1991 a shipping accident In 1991 a shipping accident occurred in the middle of the occurred in the middle of the Pacific and a few months later a Pacific and a few months later a current called the North Pacific current called the North Pacific Drift Current and the California Drift Current and the California Current had washed up 80,000 Current had washed up 80,000 pairs of shoes on the west coast of pairs of shoes on the west coast of the US.the US.

Factors Influencing Factors Influencing Surface CurrentsSurface Currents

1. Coriolis Effect- 1. Coriolis Effect- deflects currents north of the equator deflects currents north of the equator

to the right and south of the equator to the right and south of the equator to the left.to the left.

2. Continents-2. Continents- land being in the way affects currents land being in the way affects currents

and changes their path of travel.and changes their path of travel.

The Reverse FlushThe Reverse Flush

Importance of Surface Importance of Surface CurrentsCurrents

Surface currents distribute heat Surface currents distribute heat from the equator to the other areas from the equator to the other areas on the Earth. on the Earth.

Example-Iceland has a mild climate Example-Iceland has a mild climate because the warm water from the because the warm water from the Gulf Stream travels right past and Gulf Stream travels right past and warms the air over Icelandwarms the air over Iceland..

Ireland is further from the equator than Ireland is further from the equator than Scranton but has a warmer average Scranton but has a warmer average temperature.temperature.

UpwellingUpwelling

Upwelling is the circulation in the Upwelling is the circulation in the ocean that brings deep cold water ocean that brings deep cold water to the ocean surface.to the ocean surface.

This works when wind blowing This works when wind blowing offshore or parallel to the coast offshore or parallel to the coast carries water away from the land. carries water away from the land. This water is replaced with cold This water is replaced with cold deeper water rising up.deeper water rising up.

Is upwelling bad?Is upwelling bad? No- because when the cold water rises No- because when the cold water rises

it bring with it high concentrations of it bring with it high concentrations of nutrients nutrients

These nutrients help fish and other These nutrients help fish and other organisms and are great fishing organisms and are great fishing locationslocations Cold water actually is fuller with lifeCold water actually is fuller with life Tropical water can be too warm to support Tropical water can be too warm to support

most life.most life. Examples: Coast of Washington and Examples: Coast of Washington and

Oregon,Oregon, San FranciscoSan Francisco

Density CurrentsDensity Currents

Deep in the ocean water circulates Deep in the ocean water circulates not because of wind but because not because of wind but because of density differences.of density differences.