u3l5 - ocean currents

Unit 3 Lesson 5 Ocean Currents

Copyright © Houghton Mifflin Harcourt Publishing Company


Indiana Standards


• 8.2.1 Recognize and demonstrate how the sun’s energy drives convection in the atmosphere and in bodies of water, which results in ocean currents and weather patterns.

• 8.2.3 Describe the characteristics of ocean currents and identify their effects on weather patterns.

Going with the Flow


What are ocean currents?

• Ocean currents are streamlike movements of water in the ocean.

• Surface currents are ocean currents that occur at or near the surface of the ocean.

• The Gulf Stream is a surface current.


What affects surface currents?

• Surface currents are affected by continental deflections, the Coriolis effect, and global winds.

• When surface currents meet continents, they are deflected and change direction.

• The deflection of moving objects from a straight path due to Earth’s rotation is the Coriolis effect.




• How does a continent change surface currents on Earth? Could a small island change surface currents?




• In the Northern Hemisphere, currents are deflected to the right.

• In the Southern Hemisphere, currents are deflected to the left.

• Global winds can push ocean water across Earth’s surface to create surface currents.



What powers surface currents?

• The major source of energy that powers surface currents is the sun.

• The sun causes differences in temperature across Earth, which causes differences in air pressure.

• Winds form as a result of differences in air pressure and create surface currents.



Current Events


How do deep currents form?

• Deep currents are movements of ocean water below the surface caused by differences in density.

• Density is the amount of matter in a given space or volume.

• Salinity and temperature cause differing ocean water densities.


How do deep currents form?

• Salinity is a measure of the amount of dissolved salts or solids in a liquid.

• Higher salinity makes water more dense.

• Dense water sinks and can form deep water currents that flow along the ocean floor or on another layer of denser water.



What are convection currents?

• Convection currents in the ocean are the movement of water that results from density differences.

• Convection currents can be vertical, circular, or cyclical.



How do convection currents transfer energy?• Water at the ocean’s surface absorbs energy from

the sun, which can be carried to colder regions.

• As water reaches a colder region, it cools and sinks.

• As warm water moves away, cold water can rise from the bottom of the ocean, and the cycle continues.



That’s Swell


What is upwelling?

• Upwelling is the process in which winds blow warm water away from a shore, allowing cool, nutrient-rich water to rise to the surface.

• Upwelling supplies the nutrients necessary for ocean life to grow.


What is upwelling?

• What would happen to ocean life if upwelling did not occur?




Hitchin’ a Ride


• Ocean currents can carry life to other regions of Earth.

• Turtles, coconuts, and phytoplankton all ride surface currents in the ocean.

Traveling the World


What do ocean currents transport?

• Convection currents in the ocean transport energy in the form of heat.

• Ocean currents can release energy into the atmosphere, making currents an important influence on climate.

• Ocean water also transports solids, nutrients, and gases to new locations.


What do ocean currents transport?

• Trace a path on the map to show how nutrients are transported around Earth.



u3l5 - ocean currents

Science