Ocean Currents

How does ocean water move? Ocean water is never still. It is constantly moving in enormous “rivers” called currents. In fact, a drop of ocean water could travel from one end of the Earth to the other.

Two main types of Currents 1. Surface Currents 2. Density (Deep) Currents

Surface Currents Are streamlike movements of water that occur at or near the surface of the ocean and are driven by wind. They are controlled by 3 factors: A. Global Winds B. Coriolis Effect C. Continental Deflections

Currents

Global Winds http://www.windows.ucar.edu/tour/link=/earth/Atmosphere/wind.html

Global Winds These winds move continuously in the same general direction. Trade Winds blow ocean water from east to west toward the equator. Westerlies blow ocean water west to east and are located around 45 degrees latitude North and South of the equator.

Coriolis Effect The curving of moving objects from a straight path due to the Earth’s rotation. Ocean currents in the Northern Hemisphere turn clockwise. Ocean currents in the Southern Hemisphere turn counterclockwise.

Facts Global winds blowing in opposite directions in combination with the rotation of the Earth cause a powerful system of rotating currents called gyres. An example is the Gulf Stream which is part of the North Atlantic current system. The Gulf Stream carries warm water from the Caribbean up the east coast of the United States, across the northern Atlantic, and over to the west coasts of England and Europe.

Facts Continued Other well known currents include the California Current in the North Pacific Ocean that flows south along the west coast of North America and the Peru Current in the South Pacific that flows along the west coast of South America.

Continental Deflection This occurs when surface currents meet continents, they deflect, or change direction.

Surface Current Facts Surface Currents are important because they regulate the water temperature throughout the world. They distribute the sun’s heat so that the Tropics don’t get too hot and the Polar regions don’t get too cold.

Density (Deep) Currents Streamlike movement of ocean water far below the surface They are affected by temperature and salinity. Cold water is more dense than warm water because the molecules are tightly packed together.

Deep Currents Continued The more salt in the water, the more dense it will be causing it to sink. Water that is cold and salty sinks under warmer, less salty water Cold water at the poles sinks and slowly moves toward the equator.

Deep Currents Continued Warm water currents travel out from the equator along the surface, flowing toward the poles to replace the sinking cold water.

Prevailing Wind Belts of Earth

Ocean Currents