Ch. 22 Movements of the Ch. 22 Movements of the OceansOceans

Ch. 22.1 Ocean CurrentsCh. 22.1 Ocean Currents

ObjectivesObjectives

• By the end of this unit, you should be By the end of this unit, you should be able to:able to:

• Discuss how wind patterns affect Discuss how wind patterns affect surface currents.surface currents.

• Explain how differences in the Explain how differences in the density of ocean water affect the density of ocean water affect the flow of deep currents.flow of deep currents.

• CurrentsCurrents—giant streams of ocean —giant streams of ocean water.water.

• There are Surface Currents and Deep There are Surface Currents and Deep Currents.Currents.

Surface CurrentsSurface Currents

• Wind is the driving force of surface Wind is the driving force of surface currents.currents.

• Most surface currents result from Most surface currents result from global wind patterns.global wind patterns.

• Surface currents are fastest near the Surface currents are fastest near the surface, and are almost undetectable surface, and are almost undetectable 100 meters below the surface.100 meters below the surface.

Factors Affecting Ocean Factors Affecting Ocean Surface CurrentsSurface Currents

• 1. The wind belts1. The wind belts

• 2. Earth’s rotational effects2. Earth’s rotational effects

• 3. Location of the continents3. Location of the continents

• Huge circles of moving water, or Huge circles of moving water, or gyresgyres, result from the wind belts and , result from the wind belts and Coriolis force.Coriolis force.

• Gyres move clockwise in the Gyres move clockwise in the northern hemisphere, and northern hemisphere, and counterclockwise in the southern counterclockwise in the southern hemisphere.hemisphere.

• Major landmasses may deflect or Major landmasses may deflect or divide surface currents.divide surface currents.

• Trace out surface currents. Reading Trace out surface currents. Reading pg. 428-430.pg. 428-430.

Deep CurrentsDeep Currents

• Slow, cold, dense deep currents form Slow, cold, dense deep currents form when the cold polar water sinks and when the cold polar water sinks and flows beneath the warmer ocean flows beneath the warmer ocean water toward the equator.water toward the equator.

• The cold high-salinity dense water The cold high-salinity dense water stays below the warmer lower-stays below the warmer lower-density water.density water.

Antarctic Bottom WaterAntarctic Bottom Water

• Cold, salty dense water forming near Cold, salty dense water forming near Antarctica sinks and moves slowly Antarctica sinks and moves slowly northward along the bottom of the northward along the bottom of the ocean, far into the N. hemisphere. ocean, far into the N. hemisphere. The trip can take several hundred The trip can take several hundred years.years.

North Atlantic Deep WaterNorth Atlantic Deep Water

• Cold water deep current that forms in Cold water deep current that forms in the Arctic flows southward, but it the Arctic flows southward, but it rides above the denser Antarctic rides above the denser Antarctic bottom water.bottom water.

• High salinity, high density water that High salinity, high density water that forms in the Mediterranean due to forms in the Mediterranean due to evaporation sinks and flows outward evaporation sinks and flows outward through the Straits of Gibraltar. through the Straits of Gibraltar.

Turbidity CurrentsTurbidity Currents

• Caused by underwater landslides.Caused by underwater landslides.

• Dense, sediment-laden water moves Dense, sediment-laden water moves under less-dense, clear water.under less-dense, clear water.

• May cause deepening of submarine May cause deepening of submarine canyons.canyons.