An ocean current is any permanent or continuous, directed movement of ocean water that flows in one of the Earth's oceans.

Ocean Currents

2 major types

Surface

Driven by: Wind

Speed: Fast mostly

Depth: Approx. <100 m

Deep

Driven by: Differences in

Density=m/v

Speed: SLOW always

Depth: >100 m

Prevailing winds: Initial push Westerlies= west to east Trade winds= East to equator

Caused by…

Uneven heating Water near equator warms due to direct sunlight Transfers heat to poles by CONVECTION

Major causes of ocean currents

Coriolis Effect: deflection of moving objects

North= Right (clockwise) South= Left (counter clockwise)

Basin Shape: Coastline AKA the toilet bowl

Major causes of ocean currents

Ocean currents are the result of ALL of the following, except:

A. prevailing wind beltsB. the shape of the ocean basinC. Coriolis forceD. shifting tectonic plates

Review

Boundary Current

Warm

Gulf Stream Brazil Kuroshio Agulhas E. Australia

Cold/Cool

Benguela Peru Canary Greenland & Labrador W. Australia

Equatorial North South

Circumpolar Antarctic

Boundary Current

Gyre: set of four or more currents ( Draw in on map)

Gyre

Major surface currents

a)Which boundary currents influence US coast lines?

Gulf Stream &California

Review

Sandy

Irene

ReviewThe Coriolis effect causes which oceanic circulation pattern in

the Northern hemisphere shown below:

Vertical mixing of water

Changes in water temperature

Surface is warmer

Thermohaline circulation

deep ocean currents caused by: differences in density. Salinity

Increase salt=more dense

Temperature Decrease temperature= more

dense

Salinity

INCREASES (salt concentration goes up)

Evaporation Ice formation

Decreases(salt concentration goes down)

Fresh water goes in Rain Surface runoff

Ice Melts

On your map identify areas of high and low salinity

Which of the following factors increases the density and salinity in oceans?

A. river runoff into oceansB. precipitation over oceansC. icebergs melting into oceansD. evaporation of seawater

Review

Normal conditions: Wind direction:

Dominated by the trade winds (East towards Equator)

Current direction: (strong cold current towards equator)

E. Pacific water temps : Cool

Effects: N. America normal warm summer/cool winter Cooler water of South American coast Australia warmer water

Ocean-Atmosphere Patterns

El Nino Conditions:

Wind direction: Trade winds are weak or reversed (West towards Equator)

Current direction: (Weak towards equator)

E. Pacific water temps : Warm

Effects: N. America Warmer winters Floods in South America Droughts in Australia

Ocean-Atmosphere Patterns

la Nina conditions: Wind direction: VERY strong trade winds (East towards Equator)

Current direction: (Strong cold towards equator)

E. Pacific water temps : Very Cold

Effects: MUCH Cooler water of South American coast

Australia MUCH warmer water

US colder than normal winters with much more snow!

Ocean-Atmosphere Patterns