Unit 2.4: Currents and Tides

Vocabulary: 1.Current: a large stream of moving water that flows through oceans Unlike waves, currents carry water from one place to another 2.Surface Current: caused mainly by winds, affect water to a depth of several hundred meters Move in a circular pattern in the five major oceans Most flow east or west and then double back to complete the circle

Vocabulary: 1.Coriolis Effect: The earth’s rotation effects the direction of winds and currents Northern Hemisphere- Currents curve to the right Southern Hemisphere- Currents curve to the left The gulf stream is the most powerful current in the northern hemisphere

The Great Pacific Garbage Patch Great Pacific Garbage Patch Video Read the “Woman Tackles ‘ Great Garbage Patch’” Article Write 2 paragraphs Paragraph 1: Summarize the article Paragraph 2: Discuss some ways to clean up the garbage patch and keep more trash from entering the ocean

Deep Water Currents VERY DIFFERENT FROM SURFACE CURRENTS! Caused by differences in the density of ocean water, Not by wind Density depends on temperature and salinity When warm surface currents move from the equator toward one of the poles, it gradually cools. Ice forms at poles so salinity increases making the water more dense. Dense water sinks Then, cold water flows back along the ocean floor as a deep current

Upwelling: Upwelling: the movement of cold water upward from deep ocean Brings tiny ocean organisms, minerals, and other nutrients from the deeper layers of the ocean Without this motion, the surface waters of the open ocean would be scarce in nutrients Usually home to schools of fish