1. Unit 3 – Oceanography Section 3: Currents, Waves, and Tides
Earth Science
Mr. Margetan

2. Ocean Currents
Surface Currents – Movement of water on the surface, primarily caused by winds

3. Ocean Currents
Longshore Currents – Currents which run parallel to the shoreline due to energy released from waves

4. Ocean Currents
Upwelling Currents – Occur when wind moves seawater at the surface and new water from below replaces it

5. Critical Thinking #1
How might upwelling currents be beneficial to life in the ocean? Explain.

6. Ocean Currents
Deep Currents – Move slowly beneath surface, primarily caused by differing water densities

7. Critical Thinking #2
What processes might cause changes in density that form deep ocean currents?

8. Ocean Currents
Global Conveyor Belt – A connected deep ocean current that circles the entire planet

9. Waves Waves – Up and down, circular movement of energy in water
Caused primarily by wind
Also, disturbances in the ocean, earthquakes

10. Critical Thinking #3
How are ocean waves similar to seismic waves? How are they different?

11. Factors Influencing Wave Size
Strength of Wind – Speed wind is blowing
Fetch – Distance wind is blowing
Duration – Length wind is blowing

12. Parts of a Wave Crest – Highest point on a wave
Trough – Lowest point on a wave
Wavelength – Horizontal distance from crest to crest
Wave Height – Vertical distance from crest to trough

13. How do Waves Break?
Waves begin to change shape at a depth ½ its wavelength
Waves break at a depth of 1.3x its wave height

14. Critical Thinking #4
Considering how waves break, how might the shape of the ocean floor influence the shape of waves?

15. Types of Breakers
Surging Breakers – Waves roll into the shore, occurs at steep beaches
Plunging Breakers – Waves curl and break, occurs at moderate slope beaches
Spilling Breakers – Waves break far from shore, occurs at gentle slope beaches

16. Tides Tides – Daily changes in the level of the ocean surface
2 high tides and 2 low tides each day
caused by gravitational pull of primarily the moon, but also the sun

17. High Tides and Low Tides
High (Flood) Tides – Occur on side of Earth facing and opposite the moon, due to both gravity facing and centrifugal force opposite
Low (Ebb) Tides – Occur on sides halfway between the moon

18. Spring Tides and Neap Tides
Spring Tides = Highest and lowest tides, when moon and sun align
Neap Tides = Small tidal range, when moon and sun are perpendicular

19. Critical Thinking #5
Why are spring tides stronger than neap tides? Explain.