Video Field TripVideo Field Trip

1.1. How are waves created?How are waves created?

2.2. Describe the way in which the Describe the way in which the moon influences the tides.moon influences the tides.

Ocean Ocean CirculationCirculationChapter 16, Section 1Chapter 16, Section 1

Surface CurrentsSurface Currents Ocean Currents –Ocean Currents – masses of ocean masses of ocean

water that flow from one place to water that flow from one place to anotheranother

Surface Currents –Surface Currents – movements of movements of water that flow horizontally in the water that flow horizontally in the upper part of the ocean’s surfaceupper part of the ocean’s surface

Surface currents develop from friction Surface currents develop from friction between the ocean and the wind that between the ocean and the wind that blows across its surfaceblows across its surface

Some water movements are responses Some water movements are responses to local or seasonal influences, others to local or seasonal influences, others are more permanent and extend over are more permanent and extend over large portions of the oceanlarge portions of the ocean

Wind FrictionWind Friction

GyresGyres Gyre –Gyre – huge circular-moving current systems huge circular-moving current systems

which dominate the surfaces of the oceanswhich dominate the surfaces of the oceans The 5 main ocean gyres: the North Pacific Gyre, The 5 main ocean gyres: the North Pacific Gyre,

the South Pacific Gyre, the North Atlantic Gyre, the South Pacific Gyre, the North Atlantic Gyre, the South Atlantic Gyre, and the Indian Ocean the South Atlantic Gyre, and the Indian Ocean GyreGyre

Coriolis Effect –Coriolis Effect – the deflection of currents the deflection of currents away from their original course as a result of away from their original course as a result of Earth’s rotationEarth’s rotation

Because of Earth’s rotation, currents are Because of Earth’s rotation, currents are deflected to the right in the Northern deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere and to the left in the Southern HemisphereHemisphere

Therefore, gyres flow in opposite directions in Therefore, gyres flow in opposite directions in the two hemispheresthe two hemispheres

Surface Ocean Currents Surface Ocean Currents and Gyresand Gyres

Concept CheckConcept Check

What is a gyre?What is a gyre? huge circular-moving current systems huge circular-moving current systems

which dominate the surfaces of the which dominate the surfaces of the oceansoceans

Ocean Currents and Ocean Currents and ClimateClimate

When currents from low-latitude regions When currents from low-latitude regions move into higher latitudes, they transfer move into higher latitudes, they transfer heat from warmer to cooler areas of Earthheat from warmer to cooler areas of Earth

The Gulf Stream, for example, brings The Gulf Stream, for example, brings warm water from the equator up to the warm water from the equator up to the North Atlantic Current (allowing Europe North Atlantic Current (allowing Europe to be warmer in the winter than expected to be warmer in the winter than expected for those latitudes)for those latitudes)

As cold water currents move towards the As cold water currents move towards the equator, they help moderate the warm equator, they help moderate the warm temperatures of adjacent land areastemperatures of adjacent land areas

Ocean currents also play a major role in Ocean currents also play a major role in maintaining Earth’s heat balancemaintaining Earth’s heat balance

Gulf StreamGulf Stream

UpwellingUpwelling Upwelling –Upwelling – the rising of cold water from the rising of cold water from

deeper layers to replace warmer surface deeper layers to replace warmer surface waterwater

Upwelling is a common wind-induced vertical Upwelling is a common wind-induced vertical movementmovement

Coastal upwelling occurs in areas when winds Coastal upwelling occurs in areas when winds blow toward the equator and parallel to the blow toward the equator and parallel to the coast, this combined with the Coriolis effect coast, this combined with the Coriolis effect cause surface waters to move away from cause surface waters to move away from shore and be replaced by water from below shore and be replaced by water from below the surfacethe surface

Upwelling brings greater concentrations of Upwelling brings greater concentrations of dissolved nutrients, such as nitrates and dissolved nutrients, such as nitrates and phosphates to the ocean surfacephosphates to the ocean surface

California Coastal California Coastal UpwellingUpwelling

Concept CheckConcept Check

What is upwelling?What is upwelling? the rising of cold water from deeper the rising of cold water from deeper

layers to replace warmer surface waterlayers to replace warmer surface water

Density CurrentsDensity Currents

Density Currents –Density Currents – vertical currents of vertical currents of ocean water that result from density ocean water that result from density differences among water massesdifferences among water masses

Denser water sinks and slowly spreads Denser water sinks and slowly spreads out beneath the surfaceout beneath the surface

An increase in seawater density can be An increase in seawater density can be caused by a decrease in temperature or caused by a decrease in temperature or an increase in salinityan increase in salinity

Density changes due to salinity Density changes due to salinity variations are very important in the variations are very important in the polar regions, where water temperature polar regions, where water temperature remains low and relatively constantremains low and relatively constant

Density CurrentsDensity Currents

High LatitudesHigh Latitudes Most water involved in deep-ocean density Most water involved in deep-ocean density

currents begins in high latitudes at the surfacecurrents begins in high latitudes at the surface The surface waters become cold, and its The surface waters become cold, and its

salinity increases as sea ice formssalinity increases as sea ice forms The water will than sink, initiating deep-ocean The water will than sink, initiating deep-ocean

density currentsdensity currents The water’s temperature and salinity will The water’s temperature and salinity will

remain relatively unchanged while it is in the remain relatively unchanged while it is in the deep-ocean currentsdeep-ocean currents

By knowing the temperature, salinity, and By knowing the temperature, salinity, and density of a water mass, scientists are able to density of a water mass, scientists are able to map the slow circulation of water mass map the slow circulation of water mass through the oceanthrough the ocean

Sea IceSea Ice

EvaporationEvaporation Density currents can also result from Density currents can also result from

increased salinity of ocean water due to increased salinity of ocean water due to evaporationevaporation

In the Mediterranean Sea, conditions exist In the Mediterranean Sea, conditions exist where a warm, high salinity water will sink where a warm, high salinity water will sink and push its way out to the Atlantic Oceanand push its way out to the Atlantic Ocean

This water has a salinity level of 38‰, This water has a salinity level of 38‰, compared to the Atlantic having a salinity compared to the Atlantic having a salinity of 35‰, making the Mediterranean water of 35‰, making the Mediterranean water much more densemuch more dense

Scientists have tracked this water mass as Scientists have tracked this water mass as far south as Antarcticafar south as Antarctica

Mediterranean SeaMediterranean Sea

Concept CheckConcept Check

How are density currents formed?How are density currents formed?

A Conveyor BeltA Conveyor Belt A simplified model of ocean circulation A simplified model of ocean circulation

is similar to a conveyor belt that travels is similar to a conveyor belt that travels from the Atlantic Ocean through the from the Atlantic Ocean through the Indian and Pacific oceans and back Indian and Pacific oceans and back againagain

Warm water in the ocean’s upper layers Warm water in the ocean’s upper layers flow towards the polesflow towards the poles

When water reaches the poles its When water reaches the poles its temperature drops and salinity temperature drops and salinity increases, it sinks to the bottom and increases, it sinks to the bottom and moves towards the equatormoves towards the equator

The water will eventually upwells at The water will eventually upwells at warmer latitudes to complete the circuitwarmer latitudes to complete the circuit

Global Conveyor BeltGlobal Conveyor Belt

Assignment (Due Assignment (Due 2/28/08)2/28/08)

Read Chapter 16 (pg. 448-467)Read Chapter 16 (pg. 448-467) Do Chapter 16 Assessment #1-30 Do Chapter 16 Assessment #1-30

(pg. 471-472)(pg. 471-472) # 1 – 9 (pg. 473)# 1 – 9 (pg. 473)

Cool DownCool Down1.1. The average surface water temperature The average surface water temperature

off of the coast of Ecuador is 21ºC. The off of the coast of Ecuador is 21ºC. The average surface water temperature off average surface water temperature off of the coast of Brazil is about 27ºC. of the coast of Brazil is about 27ºC. Explain why there is such a difference Explain why there is such a difference in water temperature between these in water temperature between these areas at the same latitude.areas at the same latitude.

2.2. What is one thing you learned today What is one thing you learned today that you never knew? Explain.that you never knew? Explain.