Chapter 14 – The Movement Chapter 14 – The Movement of Ocean Waterof Ocean Water

Ocean CurrentsOcean Currents – The stream like movement of water in – The stream like movement of water in the oceans that are influenced by many factors.the oceans that are influenced by many factors.Thor HeyerdahlThor Heyerdahl – A Norwegian explorer who proved that – A Norwegian explorer who proved that people from Peru could have migrated to settle Polynesia people from Peru could have migrated to settle Polynesia by following the ocean currents of the Pacific.by following the ocean currents of the Pacific.Surface CurrentsSurface Currents – The horizontal movement of ocean – The horizontal movement of ocean water caused by the friction of the wind along the surface water caused by the friction of the wind along the surface of the water. The Gulf Stream Current carries 25 times the of the water. The Gulf Stream Current carries 25 times the volume of water than all of the rivers in the world volume of water than all of the rivers in the world combined!combined!Factors that control currents:Factors that control currents: 1. 1. Global windsGlobal winds – Global winds cause the water to – Global winds cause the water to move in different directions. Near the Equator, the winds move in different directions. Near the Equator, the winds blow the water from the East to the West.blow the water from the East to the West. 2. 2. Coriolis EffectCoriolis Effect – Due to the rotation of the Earth, – Due to the rotation of the Earth, global winds and hence currents, move in a curved path global winds and hence currents, move in a curved path rather than in straight lines.rather than in straight lines. 3. 3. Continental DeflectionContinental Deflection – When currents flow – When currents flow into continental land masses, they must change into continental land masses, they must change directions. directions.

Deep CurrentsDeep Currents – The movement of waters below – The movement of waters below the surface that are the surface that are NOTNOT influenced by the wind influenced by the wind but rather by density of the water. Cold but rather by density of the water. Cold temperatures and high salinity produce denser temperatures and high salinity produce denser water. As water increases in density, it will sink water. As water increases in density, it will sink due to gravity. Usually, these currents will flow due to gravity. Usually, these currents will flow along the bottom of the oceans however, when along the bottom of the oceans however, when meeting denser waters, they will flow above meeting denser waters, they will flow above them.them.

Currents & ClimatesCurrents & Climates – Surface currents greatly – Surface currents greatly affect the climate in many parts of the world. affect the climate in many parts of the world. Warm-water currents create warmer climates Warm-water currents create warmer climates along the coastal regions of many continents along the coastal regions of many continents which would normally be colder. The Gulf Stream which would normally be colder. The Gulf Stream carries warm water from the tropics and warms carries warm water from the tropics and warms the British Isles. Conversely, the California the British Isles. Conversely, the California current is a cold water current and cools our west current is a cold water current and cools our west coast!coast!

UpwellingUpwelling – The process in which cold, nutrient- – The process in which cold, nutrient-rich, deep ocean waters rise up to replace rich, deep ocean waters rise up to replace warmer surface waters moved away by local warmer surface waters moved away by local winds. These nutrients include iron and nitrates winds. These nutrients include iron and nitrates essential to the life process of phytoplankton essential to the life process of phytoplankton that form the base of the marine ecosystem food that form the base of the marine ecosystem food web.web.

El NinoEl Nino - A change in the water temperature of the - A change in the water temperature of the Pacific that produces warmer currents. Pacific that produces warmer currents. Responsible for disasters such as heavy rains Responsible for disasters such as heavy rains producing floods and mudslides in normally arid producing floods and mudslides in normally arid regions and droughts in areas normally humid regions and droughts in areas normally humid climates. This also prevents the upwelling of climates. This also prevents the upwelling of nutrients in the coastal waters of South America. nutrients in the coastal waters of South America. The N.O.A.A. set buoys in the ocean to help The N.O.A.A. set buoys in the ocean to help predict when El Nino will occur.predict when El Nino will occur.

La NinaLa Nina – A change in the Pacific waters where – A change in the Pacific waters where there are colder than normal water there are colder than normal water temperatures. This also affects weather patterns temperatures. This also affects weather patterns and usually follows an El Nino event. and usually follows an El Nino event.

WavesWaves – Created by the wind and move in a – Created by the wind and move in a circular pattern with only the energy of the circular pattern with only the energy of the wave being directed towards the shore.wave being directed towards the shore.

Wave Measurements:Wave Measurements: 1. 1. WavelengthWavelength – The distance between – The distance between

two successive wave crests.two successive wave crests. 2. 2. Wave HeightWave Height – The distance between – The distance between

the trough and crest of a wave.the trough and crest of a wave. 3. 3. Wave PeriodWave Period – The time between two – The time between two

successive wave crests.successive wave crests.As a wave approaches the shore, the energy of As a wave approaches the shore, the energy of

the wave interacts with the ocean floor and the wave interacts with the ocean floor and begins to rise upwards. Gravity will eventually begins to rise upwards. Gravity will eventually pull it over to form a breaker.pull it over to form a breaker.

UndertowUndertow – A subsurface current that forms – A subsurface current that forms when the waves washes up onto the shore and when the waves washes up onto the shore and carries sand, debris, swimmers, etc. back out to carries sand, debris, swimmers, etc. back out to the sea. the sea.

Longshore CurrentLongshore Current – A current that runs – A current that runs parallel to the shoreline.parallel to the shoreline.

WhitecapsWhitecaps – White, foaming waves with – White, foaming waves with steep crests that usually form during storms.steep crests that usually form during storms.

SwellsSwells – Long ocean waves that forms a high – Long ocean waves that forms a high wave and can travel long distances.wave and can travel long distances.

TsunamisTsunamis – Huge waves that are formed – Huge waves that are formed when a large volume of water is suddenly when a large volume of water is suddenly moved up or down usually by seismic or moved up or down usually by seismic or volcanic events.volcanic events.

Storm SurgeStorm Surge – A rise in sea level caused by – A rise in sea level caused by strong winds usually associated with a strong winds usually associated with a hurricane. hurricane.

TidesTides – The daily change in the ocean level – The daily change in the ocean level caused by the gravitational pull of the sun caused by the gravitational pull of the sun and especially the moon. Although the sun is and especially the moon. Although the sun is larger and we do orbit it, the moon is much larger and we do orbit it, the moon is much closer and has a greater gravitational closer and has a greater gravitational influence. The Earth rotates once every 24 influence. The Earth rotates once every 24 hours. hours.

Tidal RangeTidal Range – The difference in the level of – The difference in the level of the ocean between high and low tides.the ocean between high and low tides.

High TideHigh Tide – The bulge in the ocean – The bulge in the ocean when the Earth is facing the moon or when the Earth is facing the moon or opposite of.opposite of.

Low TideLow Tide – The ocean water is drawn – The ocean water is drawn away from the shore by the gravitational pull away from the shore by the gravitational pull of the moon. of the moon.

Spring TideSpring Tide – Occurs when the Earth, moon – Occurs when the Earth, moon and sun are in alignment to create the and sun are in alignment to create the largest tidal range, longest time between, largest tidal range, longest time between, and occurs twice a month during the new and occurs twice a month during the new and full moons.and full moons.

Neap TideNeap Tide – When the Earth, moon and sun – When the Earth, moon and sun form a 90form a 90° angle resulting in the smallest ° angle resulting in the smallest tidal range. Occurs twice every 28 days tidal range. Occurs twice every 28 days during the first and the third quarter moons.during the first and the third quarter moons.

Tidal BoreTidal Bore – A body of water that rushes into – A body of water that rushes into a narrow bay and causes a very sudden tidal a narrow bay and causes a very sudden tidal rise. The Bay of Fundy in Canada, has the rise. The Bay of Fundy in Canada, has the greatest tidal range due to its long, narrow, greatest tidal range due to its long, narrow, inlet. inlet.