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11.2 Ocean Currents – Student Notes Ocean Currents • There are more than _________________ which move large amounts of water predictably around the oceans. Currents move large quantities of water, minerals, solar energy, oxygen and carbon dioxide, plankton and fish. Currents are caused and driven by water density and salt content, the wind, the spin of Earth, coastlines and the moon. Largest current is the ___________________________________ in the Southern Ocean, at _________ long • _______________ are either Surface currents (___________) Deep water currents (_______________) What Makes Surface Currents Move? • ___________________________ As air warms from _______________________, it rises, and cooler air rushes to replace it. This creates wind. As the wind passes along the surface of the water, it bumps the water molecules and moves them along in the same ___________________. • ___________________________ Earth spins from West to East (counter clockwise) The________________ effect deflects winds and currents to the right/East in the Northern hemisphere (opposite in the Southern hemisphere) • ____________________________ Currents move through the oceans and around the continents like rocks in a stream. What Makes Deep Currents Move? • ____________________________: Like air, warm water rises, and cool water falls ____________________________ = cool, dense water moving on an ocean floor. Three layers of water dependent on temperature: ________________: 0 - 200 m, warmest ________________: 200 m - 1 km, rapidly cools ________________: 1 km and deeper, just above freezing • _____________________________: Adding fresh water decreases salinity Evaporation and freezing increases salinity Densest ocean waters at the poles __________________occurs when nutrient-rich cold water finally moves up to the surface Ocean Waves and Their Effect on Shaping Land • Most waves are __________________________________. • In open ocean, waves are called _______________. • The largest waves are _________________, caused by undersea earthquakes, landslides or volcanic eruptions. • Waves erode coastal areas based on the force of the waves, and the composition of the shoreline. • ____________________made up of harder rock, and erode less, but absorb most wave force. • ____________________ occur between headlands, are generally calm. • ____________________ are extra-hard rock left behind from eroded headlands. Tides • • • ____________________ are caused by gravities of Earth and the Moon. High tides occur where the Moon is closest to Earth (and opposite side) Low tides occur at 90º to the high tides. ____________________ (difference between high and low) averages 3 m in BC. The Sun’s gravity, when lined up properly, can produce extreme tides. These are called ______________________ When the Sun, Moon and Earth are not lined up, the tides are called ___________________________.