Bellringer Make sure you record today’s date, the question and your answer. If there were no land on Earth’s surface, what would the pattern of surface currents look like? Explain your answer.

3.1 Currents

Objectives: Describe surface currents. List the three factors that control surface currents. Describe deep currents. Identify the three factors that form deep currents.

Introduction Ocean current- ocean water that contains streamlike movements of water. Ocean currents are influenced by a number of factors: weather, Earth’s rotation & position of continents. With knowledge of currents, we can make predictions of where objects will float.

One Way to Explore Currents Thor Heyerdahl’s Journey: Thor Heyerdahl’s completed a long ocean journey to prove his theory that ocean currents carried the ancient Peruvians across the Pacific to Polynesia.

Surface Currents Surface current- a horizontal movement of ocean water that is caused by wind and that occurs at or near the ocean’s surface. Example: Gulf Stream Controlled by: Global Winds Coriolis Effect Continental Deflection

Global Winds Different winds cause surface currents to flow in different directions. In much the same way that you create ripples, winds that blow across Earth’s surface create surface currents in the ocean Near the equator winds blow east to west and near the poles it is west to east

The Coriolis Effect The Earth’s rotation causes wind and surface currents to move in curved paths rather than in straight lines. It causes surface currents in the Northern Hemisphere to turn clockwise, and in the Southern Hemisphere to turn counterclockwise.

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

Taking Temperatures Both warm-water and cold-water currents travel from one ocean to another.

Deep Currents Deep Ocean Currents- streamlike movements of ocean water located far below the surface are called deep currents. Factors that form Deep Ocean Currents are: Temperature Salinity Density

Formation & Movement of Deep Currents Deep Ocean Currents- streamlike movements of ocean water located far below the surface are called deep currents. Differences in temperature and salinity— and the resulting differences in density— cause variations in the movement of deep currents. The next slide shows how deep currents are formed.

How Deep Currents Form

Polar Regions The warmer, less-dense water in surface currents cools and becomes the colder, denser water in deep ocean currents. http://youtu.be/KuSB6HNRT2s