How Are Ocean Currents Produced?

Thermohaline Circulation

Currents in the ocean circulate areas of cold and warm water to regulate the climates around the globe. These currents move based upon the density of the water. Cold water with a higher salt content has more density than warmer, less salty water. Waters with more density sink below those of lower density, but they also move to areas of lower density. This results in warm ocean water moving toward colder areas, and as it moves, some of its heat dissipates into the atmosphere. This aids in creating climates of coastal regions. Colder water will sink to the bottom of the ocean where it continues to circle the globe.

The Sun

The sun unevenly heats the Earth. Ocean waters and air near the equator receive more sunlight and get warmer than waters and air near the poles. The warm air moves to cooler areas, creating winds. These winds push the top 100 meters (325 feet) of the ocean's waters with them in their movement. The pushed surface water flow in predictable currents. The rotation of the Earth influences the direction of these currents by the Coriolis Effect.

The Coriolis Effect

Without the spinning of the Earth from its rotation, the ocean currents would move in straight lines similar to lines of latitude, toward the poles. As the Earth turns, it curves the ocean currents, to the right in the Northern hemisphere or the left in the Southern. This creates gyres in the ocean currents as seen in the illustration.

References

• Waterencylcopedia: Ocean Currents
• The Coriolis Effect
• Thermohaline Circulation