Chapter 18: Ocean Motion

1. Chapter 18: Ocean Motion Section 1: Ocean Water Section 2: Ocean Currents

2. Importance of the Ocean • Source of: • Food • Energy (oil and natural gas) • Minerals (copper, gold, salt) • Transportation of goods

3. Origin of Oceans 4 billion years ago the water vapor that spewed out of volcanoes on early Earth. The water vapor was stored in the atmosphere and over millions of years it cooled and condensed into storm clouds. Torrential rains began to fall. Oceans formed as this water filled low areas or basins.

4. Composition of Oceans • Dissolved Gases: • Oxygen • Carbon Dioxide • Nitrogen • How does oxygen get into the ocean? • Directly from the atmosphere • From organisms that photosynthesize (oxygen is the byproduct of photosynthesis) • How does Carbon Dioxide get into the ocean? • From the atmosphere • From organisms with they respire (fish) • How does Nitrogen get into the ocean? • The atmosphere

5. Composition of the Oceans(Continued) • Dissolved Salts: • Chloride • Sodium • Sulfate • Magnesium • Calcium • Potassium • Where do the dissolved salts come from? • Rocks that are dissolved slowly by rivers and ground water • Rivers carry the chemicals to the oceans • Erupting volcanoes can add other ions such as bromide and chloride.

6. Salts • Hydrogen and Oxygen make up most of the ocean water. • Other ions are found dissolved in seawater. • When seawater is evaporated, these ions combine to form materials called salts. • Sodium (30.6%) and Chloride (55%) make up the most of the ions. • Salinity: a measure of the amount of salts dissolved in seawater. • g/kg • 1 kg of ocean water contains about 35 g of dissolved salts or 3.5% • Oceans are not growing saltier.

7. Removal of Elements • Oceans are in a steady state even though volcanoes, rivers and the atmosphere constantly add material. • Elements are added at the same rate as they are removed. • How are elements used? • Marine organisms use calcium ions to make body parts like shells or form bones.

8. Desalination and Desalination Plants • Desalination is when salt is removed from the ocean. • Because freshwater is in demand scientists are working on technology to remove salt to make seawater drinkable. • Desalination Plants use solar energy to evaporate seawater using a glass roof over a pool of seawater. • The seawater is piped into the building • The sun heats and evaporates the water; leaving the salt behind. • When the water vapor condenses, it runs along the sloped roof and collects in side containers.

9. Desalination Plants(Continued) • Other plants desalinate water by passing it through a membrane that removes the dissolved salts. • Most common practice used today. • Another method used is melting frozen seawater. • As seawater freezes the ice crystals contain much less salt than the remaining water. • The salty, unfrozen water then can be separated from the ice. • The ice can be washed and melted to produce freshwater.

10. Section 2: Ocean Currents

11. Surface Currents • Ocean currents are like a river within the ocean. • Surface currents: • Move water horizontally – parallel to the Earth’s surface. • Powered by the wind. • Both warm and cold currents. • The currents on the ocean's surface are related to the general circulation of winds on Earth. • Move only the upper few hundred meters of water. • Sailors use these currents along with winds to sail more efficiently.

12. How do Surface Currents Form? Coriolis Effect – shifting of winds and surface currents from their expected paths caused by the rotation of the Earth. Because Earth rotates toward the East, winds appear to curve to the RIGHT north of equator and LEFT south of the equator. Surface winds can cause water to pile up in certain parts of the ocean. Gravity pulls water off the pile and the Coriolis effects turns the water causing surface water in the oceans to spiral around the piles of water. The Coriolis effect causes currents north of the equator to turn to the right and currents south of the equator to turn to the left.

14. Tracking Surface Currents Items that wash up on beaches provide information about ocean currents. Message in a Bottle

15. Warm and Cold Surface Currents • Currents on the west coasts of continents begin near the poles where the water is colder. • Currents on the eastern coasts of continents originate near the equator where the water is warmer. • Distributing heat from equatorial regions to other areas of Earth. • As warm water flows away from the equator, heat is released to the atmosphere and is warmed, influencing climate.

16. Upwelling A vertical circulation in the ocean that brings deep, cold water to the surface. This cold water replaces water that has moved away from shore. Contains high concentrations of nutrients from dead organisms that sand to the bottom of the ocean floor. Nutrients promote primary production and plankton growth which in turn attracts fish. Examples: Oregon, Washington, and Peru.

18. Density Currents Deep in the ocean, waters circulate not because of wind but because of density differences. When a mass of seawater becomes more dense than the surrounding water. Gravity causes more dense seawater to sink beneath less dense seawater. The deep, dense water slowly spreads to the rest of the ocean. Density increases as salinity increases and when temperature decreases.

19. Deep Waters A density current that begins in Antarctica where the most dense ocean water forms during the winter can take 1000 years before reaching the equator. Calculating Density Page 522 Density = Mass/Volume

20. http://www.youtube.com/watch?v=w_8mw-1HYFg&feature=results_main&playnext=1&list=PL3E19AB54C205BD31 (Bill Nye)

21. Assignment Page 517 Self-Check # 1-5 Page 522 Calculate Density # 1 and 2 Page 523 Self-Check # 1-5 Worksheet on Currents