EarthSpace SWBAT Explain how winds and the Coriolis effect influence surface currents Discuss the temperatures of coastal waters Describe density currents and how they affect Earth Surface Currents ID: 720127
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Slide1
Notes on “Ocean Currents”
Earth/SpaceSlide2
S.W.B.A.T.
Explain how winds and the Coriolis effect influence surface currents
Discuss the temperatures of coastal waters
Describe density currents and how they affect EarthSlide3
Surface Currents
Ocean currents are like rivers within the oceansSurface Currents - water that moves horizontally or parallel to Earth’s surface by windSlide4
Surface Currents
Only a few hundred meters of surface water is moved
Some seeds and plants are carried between continents by surface currentsSlide5
Major Surface Currents of Earth’s OceansSlide6
Surface Currents
Because Earth rotates west to east surface winds causes water to shiftCoriolis
E
ffect
-
shifting of winds & waters due to Earth’s rotationSlide7
Surface Currents
Wind and surface currents will deflect to the right (or “clockwise”) in the northern hemisphere and to the left
(counter-clockwise) in the southern hemisphereSlide8
Coriolis
Effect or “Force”
Video (2:12) “
Coriolis
Effect Explained
”Slide9
Surface Currents
Gulf Stream – flows up the U.S. east coast and keeps Britain & Northern Europe’s climate mild
The Gulf Stream is the world’s most powerful ocean surface currentSlide10
Surface Currents
Satellites can track currents based on ocean temperature
Surface currents can also be tracked by using messages in bottles and other flotation devicesSlide11
Ocean Surface Temperatures - Satellite DataSlide12
Surface Currents
Warm currents (red) originate near the equator and flow towards the poles
This distributes heat into the atmosphere and influences climate
Cold currents (blue) flow towards the equator & heats up creating a cycleSlide13
Upwelling
Upwelling
occurs when deep, cold ocean water is brought to the surface
Winds along some coasts will move warm water away from the surfaceSlide14
Upwelling
Cold bottom water will rise up to take the place of the warmer waterThis water contains organisms that have died, sank to the bottom and decayed
Nutrients from upwelling attract fishSlide15
Areas of Upwelling (in Red) and Major World FisheriesSlide16
Density Currents
Density currents – when a mass of seawater circulates because of density differencesDensity increases with higher
salinity
Density also increases with a decrease in
temperature
Also known as
“
t
hermohaline
”
currents (“thermo” = temperature; “
haline
” = salinity)Slide17
Density Currents
Changes in temperature and salinity work together to create density currents
These currents move very slowly and can take many years to circulateSlide18
Density Currents
Global Ocean Conveyor Belt – starts in the winter in the arctic regions
Seawater freezes leaving behind high-salinity water that sinks
This deep-ocean conveyor belt takes about 1000 years to circulate the Earth once!Slide19
Deep-Water Global Ocean Conveyor Belt
Video (2:40) “Ocean Odyssey: Density Current
”Slide20
Density Currents
Mediterranean
water is very high in salinity due to a warm climate and evaporation
This causes an
intermediate layer
to form on top of the cold water in the AtlanticSlide21
Density Currents
Thermohaline (density) currents are very important in replenishing nutrients from warmer surface waters
These currents also help in regulating global climate
Global warming may affect density currents causing further climate changeSlide22
Class Activity
A river flows into the ocean
Predict what will happen to this layer of fresh-water
Explain your prediction