Currents

Ocean Currents Ocean currents are a movement of ocean water that follows a regular pattern. There are two types of currents: surface currents and deep (density) currents. Instructional Approach(s): The teacher should present the information on the slide while the students record the important information on their notes.

Ocean Currents: Surface Currents Surface currents move water horizontally – parallel to Earth’s surface Surface currents are powered by wind The wind forces the ocean to move in huge, circular patterns http://www.livescience.com/19662-animation-reveals-ocean-currents.html Instructional Approach(s): The teacher should present the information on the slide while the students record the important information on their notes.

Three Factors that affect Surface Currents Global Winds Winds blow across the Earth’s surface Winds blow water east to west at the equator Winds blow water west to east closer to the poles

2. Coriolis Effect The curving path of a moving object from an otherwise straight path due to Earth’s position http://www.youtube.com/watch?v=dt_XJp77-mk Southern Hemisphere – currents turn counter-clockwise Northern Hemisphere – currents turn clockwise http://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm

3. Continental Deflection When surface currents meet continents, the currents deflect, or change direction

Ocean Currents: Surface Currents Instructional Approach(s): The teacher should use the diagram to illustrate surface currents.

Temperature Affects Surface Currents Warm-water currents begin near the equator and carry warm water to the other parts of the ocean Cold-water currents begin closer to the poles and carry cool water to other parts of the ocean.

Surface Currents Notice again the Red arrows and the Blue arrows showing the movement of warm water and the movement of cold water Instructional Approach(s): The teacher should use the diagram to illustrate the concept of surface currents (warm and cold water)

Deep (density) Currents Deep currents are a stream like movement of ocean water far below the surface. Deep in the ocean, waters circulate not because of wind but because of density differences. A density current forms when a mass of seawater becomes more dense (density increases) than the surrounding water. More dense seawater sinks beneath less dense seawater. Density currents circulate ocean water slowly. Instructional Approach(s): The teacher should present the information on the slide while the students record the important information on their notes.

Density is affected by temperature and salinity. Ocean depth increases Density increases Temperature increases Salinity increases Salinity increases Density increases Temperature decreases Density decreases Instructional Approach(s): The teacher should review the information on the slide while the students record the important information on their notes. Temperature decreases because cold water is more dense and sinks

Density Currents Instructional Approach(s): The teacher should use the diagram to illustrate density currents.

Surface currents carry warm water to polar regions. Warm water replaces cold water that sinks to the ocean floor. Deep currents carry cold water along the ocean floor from polar regions. Water from deep currents rises to replace water leaving surface currents. Instructional Approach(s): The teacher should use the diagram to illustrate surface currents and density currents.

Waves & Currents Video http://studyjams.scholastic.com/studyjams/jams/science/weather-and-climate/waves-and-currents.htm Instructional Approach(s): The teacher should show the video to reinforce the concept of waves and currents