Chapter 18: Ocean MotionSection 1: Ocean Water

Section 2: Ocean Currents

Source of: Food Energy (oil and natural gas) Minerals (copper, gold, salt) Transportation of goods

Importance of the Ocean

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.

Origin 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

Composition of Oceans

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.

Composition of the Oceans(Continued)

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.

Salts

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.

Removal of Elements

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.

Desalination and Desalination Plants

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.

Desalination Plants(Continued)

Section 2: Ocean 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.

Surface Currents

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.

How do Surface Currents Form?

Items that wash up on beaches provide information about ocean currents.

Message in a Bottle

Tracking 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.

Warm and Cold Surface Currents

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.

Upwelling

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.

Density Currents

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

Deep Waters

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

Page 517 Self-Check # 1-5Page 522 Calculate Density # 1 and 2

Page 523 Self-Check # 1-5Worksheet on Currents

Assignment