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

gyre

A large circular surface current pattern found in each ocean

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.