OCEAN CURRENTSSection 4 – Chapter 13

What is a current?•A current is a large stream of moving water.

•Currents actually MOVE water – waves do NOT move water.

•There are 2 main types of currents:

1)Surface currents2)Deep currents

SURFACE CURRENTS•Affect water several hundred meters deep.

•Driven mainly by the wind.•Most of them flow East or West

Coriolis Effect•The Coriolis Effect is the effect of Earth’s

rotation on the direction of the currents.•Northern Hemisphere – currents flow to

the right; clockwise•Southern Hemisphere – currents flow to

the left; counterclockwise

Click the Earthfor video explanation!

Video Demo of Coriolis Effect

The GULF STREAM•The largest, most powerful surface

current in the Atlantic Ocean.•It carries warm water from Mexico to

Carribean then northward along coast of US – at NC it curves outward due to Coriolis Effect!

Gulf Stream

Surface Currents Affect Climate•Warm/Cold water currents will warm or

cool the air above them and influence the climate on land.

•Air over warm currents tend to pick up moisture and bring rain to land.

•Cold currents will cool the air which can’t pick up as much moisture which results in cooler, drier weather.

El Nino•Unusual wind patterns will change the

currents flow in the Pacific Ocean. • It happens every 2-7 years.•This change causes weather patterns to

shift towards more severe weather occurances like extra rainy(flooding/mudslides), mild winters, incident of tornadoes increases, etc.

Ocean Temp Comparison

El N

ino

– Tem

ps

are

high

er

Wind Patterns Shift

DEEP CURRENTS•Caused by differences in density of ocean

water due to difference in temperature/salinity.

•Flow more slowly than surface currents – one circuit around can take up to 1000 years!

•Cold water flows from the poles towards the equator.

•Sometimes called “thermohaline” currents or the “conveyor belt”

UPWELLING•Movement of cold, deep water upwards

towards the surface.•Important b/c it brings nutrients from the

ocean floor up towards the surface.•Fish & other organisms depend on this

upwelling for their survival.•Many upwelling regions contain hundreds

of schools of fish.