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If there were no land on Earth’s surface, what would the pattern of surface currents look like? Explain your answer.

3.1 Currents

Objectives:• Describe surface currents.

• List the three factors that control

surface currents.

• Describe deep currents.

• Identify the three factors that form

deep currents.

Introduction• Ocean current- ocean water that contains

streamlike movements of water.

• Ocean currents are influenced by a number

of factors: weather, Earth’s rotation &

position of continents.

• With knowledge of currents, we can make

predictions of where objects will float.

One Way to Explore Currents• Thor Heyerdahl’s Journey: Thor

Heyerdahl’s completed a long ocean

journey to prove his theory that

ocean currents carried the ancient

Peruvians across the Pacific to

Polynesia.

Surface Currents• Surface current- a horizontal movement of

ocean water that is caused by wind and that

occurs at or near the ocean’s surface.

Example: Gulf Stream

• Controlled by:

• Global Winds

• Coriolis Effect

• Continental Deflection

Global Winds• Different winds cause surface currents

to flow in different directions.

• In much the same way that you create

ripples, winds that blow across Earth’s

surface create surface currents in the

ocean

• Near the equator winds blow east to

west and near the poles it is west to

east

The Coriolis Effect• The Earth’s rotation causes wind

and surface currents to move in

curved paths rather than in straight

lines.

• It causes surface currents in the

Northern Hemisphere to turn

clockwise, and in the Southern

Hemisphere to turn

counterclockwise.

Continental Deflection• When surface currents meet

continents, the currents deflect, or

change direction.

Taking Temperatures• Both warm-water and cold-water

currents travel from one ocean to

another.

Deep Currents• Deep Ocean Currents- streamlike

movements of ocean water located

far below the surface are called

deep currents.

• Factors that form Deep Ocean

Currents are:

• Temperature

• Salinity

• Density

Formation & Movement of Deep Currents• Deep Ocean Currents- streamlike

movements of ocean water located

far below the surface are called deep

currents.

• Differences in temperature and

salinity— and the resulting

differences in density— cause

variations in the movement of deep

currents. The next slide shows how

deep currents are formed.

How Deep Currents Form

Polar Regions• The warmer, less-dense water in

surface currents cools and becomes

the colder, denser water in deep

ocean currents.

http://youtu.be/KuSB6HNRT2s