Ocean Circulation – Ch. 16.1

Ag Earth Science – Chapter 15.2

ocean current

 Mass of ocean water that flows from one place to another

surface current

 Movement of water that flows horizontally in the upper part of the ocean’s surface

 A large circular surface current pattern found in each ocean

gyre

Coriolis effect

 The apparent deflective force of earth’s rotation on all free-moving objects, including the atmosphere and oceans; Deflection is to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

upwelling

 The rising of cold water from deeper layers to replace warmer surface water that has been moved.

density current

 Current of ocean water that results from density differences among water masses

Surface Circulation

 Ocean Currents – masses of ocean water that flow from one place to another.

 Surface Currents – movements of water that flow horizontally in the upper part of the ocean’s surface.

 Surface currents develop from friction between the ocean and the wind that blows across its surface.

Surface Circulation

 Gyres – Huge circular-moving current systems that dominate the surfaces of the oceans  Coriolis Effect – the deflection of currents away from their original course as a result of the Earth’s rotation.

 Because of the earth’s rotation, currents are deflected to right in the Northern Hemisphere and to the left in the Southern Hemisphere.

Surface Circulation

 When currents from low latitude regions move into higher-latitudes, they transfer heat from warmer to cooler areas of Earth.

 As cold water currents travel toward the equator, they help moderate the warm temperatures of adjacent land areas.

Surface Circulation

 Upwelling – the rising of cold water from deeper layers to replace warmer surface water.

 Upwelling brings greater concentrations of dissolved nutrients, such as nitrates and phosphates, to the ocean surface.

Deep-Ocean Circulation

 Density Currents – vertical currents of water that result from density differences among water masses.

 Cold, salty water is more dense than warmer water, so it drops down vertically into the depths of the ocean and is replaced by less dense water.

 Evaporation of ocean water in warm surface areas also can increase salinity (density) and causes the denser water to drop and be replaced by less dense water.

Conveyor Belt Model

 Simplified model of ocean circulation.

 Travels from Atlantic Ocean through Indian and Pacific Oceans and back again.  Warm water from oceans’ upper layers moves to poles  When it reaches the poles, temperature decreases and salinity increases.  Water sinks and moves towards the equator from the poles.