Winds are the main cause of ocean surface currents. Friction between the air and the water
makes the water move.
inertia- the tendency for objects in motion to remain in motion and for objects that are not
moving to remain at rest.
Currents remain in motion after winds stop blowing due to inertia.
The deeper you go in the ocean, the slower the currents flow.
Factors affecting Ocean Surface Currents:
1) Earth�s major wind belts
2) Coriolis effect
When you combine the effect of the wind with the Coriolis effect you get a combination
effect called the Ekman spiral.
Ekman spiral-combination effect of wind and the Coriolis effect on surface currents.
Makes water flow 45 degrees to 90 degrees to the wind direction.
gyres- huge circles of moving water.
In the Northern Hemisphere the flow of gyres is clockwise
In the Southern Hemisphere the flow of gyres is counter clockwise
3) Earth�s land masses- when an ocean surface current flows against a landmass, the
current is deflected and divided
Warm water currents bring warmth to the land they flow by.
Cold water currents bring colder air to the lands they flow by.
eddies- circular movements of water formed by friction between water flowing in a current
and the water next to it.
Formation of eddies:
1) friction between current and adjacent water is produced
2) circular motion begins
3) eddies pinch off from the water they were originally in
4) current boundary reforms and eddies continue to rotate and wander and continue for
months
Deep currents move very slowly beneath the surface of the ocean and are caused by
differences in the density of water.
Deep currents flow very slowly beneath warmer ocean water and flow toward the equator.
The water is very cold and dense so it sinks.
Density:
1) molecules move slower
2) molecules get packed together
3) matter gets heavier and sinks
3 types of deep currents:
1) Antarctic bottom water: temperature is about -2 degrees Celsius with very high salinity.
It sinks around Antarctica very, very slowly then slowly moves northward. Travels
thousands of kilometers to about 40 degrees north and takes several hundred years to
make the trip.
2) North Atlantic deep water: very cold and salty, just south of Greenland. It sinks and
flows southward below the Gulf Stream.
Most deep currents flow in opposite direction than that of the surface current flowing
above them.
3) Turbidity Current- strong current caused by an underwater landslide.
Upwelling- when deep water moves up to replace surface water flowing away.
Water that upwells carries high amounts of nutrients. This leads to the formation of
phytoplankton (red, orange, yellow).