Transcript Where Does My Boat Go? Ocean Currents

What forces cause
the ocean to move?
 Gravitational pull of the Moon and Sun
 Wind (friction between air and water)
 Coriolis Effect (spin of Earth)
 Differences in Water Temperatures (density
differences)
 Differences in Water Salinity (density differences)
Edited 03.18.2010
Gravitational pull
of the moon & Sun causes the TIDES?
Horizontal Surface Currents (gyres)
caused by Wind and Coriolis Effect
What is the Coriolis Effect?
Because Earth spins, the circulating air is deflected resulting in
curved paths of air, called the Coriolis Effect. This deflection of the
atmosphere sets up the complex global wind patterns which drive
surface ocean currents.
If Earth remained still
the atmosphere would only circulate
Global winds
drag on
the poles
water’s
causing ocean water
Between
Earth’s
andsurface,
Earth’s equator
in aup
simple
backdirection
and forth pattern.
to move and build
in the
that the wind is blowing.
Gyres Impact our Climate by
Moderating the Earth's temperatures by
transferring heat by convection and conduction
As surface currents move the water, the water
absorbs heat in the tropical regions and
releases this heat in colder environments near the poles.
Another effect of gyres…
Vertical/Deep Water Currents are…
 Responsible for circulating 90% of Earth's ocean water
 Don’t forget how deep the ocean is!!!!!!!!!!!!
 An influence not only weather patterns but the overall
health of the oceans
 Set in motion by variations in water density, which is
directly related to temperature and salinity
Differences in salinity
Why is the
water at
tropical
latitudes
saltier?
Differences in salinity
Why is the
water at
the poles
extremely
dense?
Putting it all together results in
The Great Conveyor Belt
 Sea water entering polar regions cools or freezes becoming saltier and denser as fresh
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
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
water is frozen into sea ice
This colder and saltier water tends to sink
A global "conveyor belt" is set in motion when deep cold salty water forms in the North
Atlantic, sinks, moves south, and circulates around Antarctica, and then moves
northward to the Indian, Pacific, and Atlantic basins
It can take a thousand years for water from the North Atlantic to find its way into the
North Pacific.
Warm surface currents invariably flow from the tropics to the higher latitudes, driven
mainly by atmospheric winds, as well as the earth's rotation.
Putting it all together results in
The Great Conveyor Belt
Result of wind, Coriolis effect, temperature and salinity differences