Ocean Currents

What Are Ocean Currents?

●Ocean currents are like rivers in the sea

●They are continuous movements of water in
the ocean

●Two main types: Currents

○Surface currents (top 400 meters)

○Deep currents (below 400 meters)

●Currents move in specific patterns around the
globe

What Causes Ocean Currents?

●Wind patterns

○As the Earth rotates, the air
circulates

○Heating and cooling changes the
density of the air as it moves to
convection.

Vocabulary:
Density: how much matter something
has and how much space it take up

Convection: a current in a fluid due to
heat

What Causes Ocean Currents?

●Earth's rotation (Coriolis Effect)

○Complex global wind patterns which
drive surface ocean currents

Earth’s rotation makes the wind curve and causes the ocean’s
surface currents curve.

klru.pbslearningmedia.org/resource/nvcl.sci.earth.coriolis/the-corioli
s-effect/?student=true&focus=true

What Causes Ocean Currents?

●Water temperature differences

●Salt content (salinity)

Cold water is denser than warm water, and salty
water is denser than freshwater

What Causes Ocean Currents?

●Ocean bottom topography

○the shape and features of the ocean floor, just like land has mountains, valleys, and plains.

○includes underwater mountains (mid-ocean ridges), deep valleys (trenches), flat areas
(abyssal plains), and tall, isolated peaks (seamounts).

●Gravity

Surface Currents

●Driven mainly by wind

○winds blow constantly from the same direction on the ocean's surface for long time, ocean
surface currents can be produced.

●Move water horizontally

Surface Currents

●Affect the top layer of ocean

○Examples:

■Gulf Stream

■California Current

■Kuroshio Current

Deep Ocean Currents

●Also called thermohaline circulation

●Caused by differences in:

○Water density

○Temperature

○Salt content

●Move more slowly than surface currents

●Can take hundreds of years to complete their cycle

The Global Conveyor Belt (thermohaline circulation)
●Connects all major oceans

○Moves water around the globe

○Important for:

■Distributing heat

■Moving nutrients

■Supporting marine life