Currents

Activating Strategy: Watch the video below then answer the questions. http://video.disney.com/watch/catching-the-eac-4bb39d25a179ea8833003b15 Where is this event happening? What causes the condition shown in the video? What do you think is the importance of the condition shown? Instructional Approach(s): The teacher should show the video clip while the students answer the two questions. The teacher may want to do this as a Think, Pair, Share. The students would “think” and answer the two questions on their own while watching the video. Then the teacher should spend no more than 2-3 minutes doing “Pair and Share”

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.

Four Factors that affect Surface Currents Global Winds Global 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 Northern Hemisphere – currents turn clockwise Southern Hemisphere – currents turn counter-clockwise http://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm

3. Continental Deflection When surface currents meet continents, and the current is deflected (bounces back), and changes direction

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

4. 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. Warm wants to move where it is cold and cold wants to move where it is warm. Instructional Approach(s): The teacher should use the diagram to illustrate the concept of surface currents (warm and cold water)

Write a three sentence summary about surface currents.

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 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

Exit Ticket (non-graded) Explain briefly what causes surface currents and deep (density) currents to form. (2-3 sentence summary) Looking for: Surface currents are caused by global winds, continental deflection, the Coriolis effect, and temperature of the water. Deep density currents are formed by an increase in density which is caused by decrease in temperature OR an increase in salinity,