Ch 16.1 Ocean Circulation

Vocabulary:

ocean current

surface current

gyre

Coriolis Effect

upwelling

density current

Objectives:

How do surface currents develop?

From friction between the ocean and the wind that blows across the surface.

How do ocean currents affect climate?

When currents from low latitude regions move into higher latitude regions, they transfer heat from warmer to cooler areas on Earth.

Example.  The Gulf stream brings warm water from the Gulf of Mexico to Great Britain.  This allows Great Britain to have a warmer winter than regions such as Alaska and Newfoundland which are at the same latitude.

The converse is also true as cold water currents help along the coasts of West Africa, Peru, and California, USA experience cooler summers than similar regions that do not have such currents

Why is upwelling important?

Upwelling is a wind induced vertical movement which causes the rising of cold water from deeper layers to replace warm surface water.

This brings greater concentrations of dissolved nutrients such as nitrates and phosphates to the ocean surface.  This increase in nutrients supports more plankton which in turn supports more fish.

How are density currents formed?

Density currents are vertical currents of ocean water that result from density differences among water masses.

Density of seawater can be increased by a decrease in temperature or an increase in salinity.

Questions:

Using page 449, list the four currents that make up the Indian Ocean Gyre.

Find the West Wind Drift.  Explain why it is the only current that completely encircles Earth.

How would the fishing industry be affected if upwelling stopped?  Explain.

Animation of gyre:

http://www.roebuckclasses.com/105/animations/wind.htm

Review Videos:

NASA Sci files

NASA Sci files:  Density currents:

https://www.youtube.com/watch?v=FuOX23yXhZ8&list=PL65770374240A3EB9

Gyres

https://www.youtube.com/watch?v=YCorkyBe66o&index=5&list=PL65770374240A3EB9