1. Ocean Currents
Chapter 5
Notes

2. Ocean Currents
Movement of ocean water that follows a regular pattern

3. First Explorer
1940 Thor Heyerdahl theorized that humans migrated across oceans using currents
1947 he left Peru in a sail boat sailed for 97 days until he reached the island of Polynesia.

4. Surface Currents
Horizontal movement caused by winds near the oceans surface
Two examples: Gulf Stream and Brazil Current
Three Factors: global winds, Coriolis effect, continental deflections

5. Global Winds Winds cause the currents to flow in different directions
Equator= east to west
Poles = west to east

6. Coriolis Effect
Curving of moving objects from a straight path due to Earth’s rotation
Northern hemisphere- clockwise
Southern hemisphere-counterclockwise

7. Continental Deflections
Currents change directions by hitting the continents or landmasses

9. Deep Currents
A stream like movement of ocean water far below the surface
Form where water density increases
Decreasing water temperature and increasing water salinity increase density.
Examples: North Atlantic Deep Water and Antarctic Bottom Water

10. Deep Currents can form by
Decreasing temperature
Increasing salinity through freezing
Increasing salinity through evaporation

12. Currents and Climates
Surface currents gently cool or warm the coastal areas year round
Some surface currents change their circulation pattern causing changes in the atmosphere that affect the climate in many parts of the world.

13. Warm Water Currents and Climates
Warm water currents create warmer climates in coastal areas.

14. Cold Water Currents and Climates
Cold water current bring cooler climates into areas.

15. Upwelling
An upwelling is the movement of deep, cold, and nutrient rich water to the surface of the ocean
This is important for organisms. Allows for the plankton and zooplankton to feed fish and other organisms.

16. El Nino
El Nino: a change in the water temperature in the Pacific Ocean that produces a warm current
Occurs ever 2-12 years
Can last a year or longer
La Nina : A change in the eastern Pacific Ocean in which the surface water temperature becomes usually cool
Usually follows El Nino

17. Effects of El Nino Flash floods
Mudslides in the United States and Peru
Droughts in Indonesia and Australia
Lack of upwelling off the coast of South America

18. El Nino

19. Wave Parts of a Wave Picture of a wave Trough: lowest point on a wave
Crest: highest point on a wave
Wavelength: distance between two crests
Wave height: the vertical distance between the crest and the trough

20. Types of Waves Wind forms MOST ocean waves
Waves can move in one direction and can generate many different events that can be dangerous to humans.

21. Deep water waves and Shallow water waves
Deep water waves are waves that move in water deeper than one-half their wavelength.
As these waves turn into shallow water waves the waves start to interact with the ocean floor.
This interaction allows the wave to increase in height. Eventually gravity will pull the crests downward at the “Breaker zone”. Waves continue to “break” until they reach the surf or beach.

22. Shore Currents
Undertow: when waves crash on the beach head on, the water flows back to the ocean underneath new incoming waves

23. Long shore Currents
Waves that hit the shore at an angle cause the water to move along the shore in a current that is near and parallel to the shoreline
Down side: spreads trash and erodes the sand.

24. Open Ocean Waves Whitecaps: Bubbles in the crests of breaking waves
Form during storms
Very short lived

25. Open Ocean Waves
Swells: Rolling waves that move steadily across the ocean
Have longer wavelengths
Travel for thousands of kilometers

26. Tsunamis
Waves that form when a large volume of ocean water is suddenly moved up or down
Causes: Underwater Earthquakes, Volcanic Eruptions, landslides, underwater explosions,

27. Tsunamis

28. Storm Surges
A local rise in sea level near the shore that is caused by strong winds from a storm
Contain a lot of energy
Follow a hurricane
Can be 8 m in height