1. Currents
Currents

2. Driven by forces of wind, tides, and gravity,
currents keep the ocean in constant motion.
7 Major Currents
West Wind Drift (AKA=Antarctic Circumpolar Current
East Wind Drift
North and South Equatorial Currents
Peru Current
Kuroshio Current-near Japan’s coast, travels up to 75 miles a day at 3 mi/hr.
Gulf Stream

3. These currents flow in large rotating loops called GYRES
(Clockwise in N. Hemi. and counterclockwise in S. Hemi.) WHY?

4. Due to the Coriolus Effect
The Coriolis effect is most apparent in the path of an object moving longitudinally. On the Earth an object that moves along a north-south path, or longitudinal line, will undergo apparent deflection to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

5. COASTAL CURRENTS
Some currents occur along the coast and only affect limited areas.
LONGSHORE Current-caused by waves striking a beach at an angle front and part of the wave hits the shallow water first and slows down. The rest of the wave bends and comes onto the shore creating a current that parallels the beach. Longshore currents often form sandbars.
RIP Currents- are dangerous effects of Longshore currents. This Rip current or Rip tide can carry swimmers out to sea. Swimmers should swim parallel to the shore until the rip current is no longer felt and they can swim safely to shore.

6. Rip Currents

7. Fridtjof Nansen Special made boat named the Fram
Froze it in ice to drift to North Pole
Never made it, always degrees to the right
Why? Coriolus effect

8. Ekman Spiral

9. Waves
Ch 9

10. Wave Anatomy

11. Wave Anatomy

12. Wave period: is the time (in seconds) between successive waves.
*Ideal surfing conditions are when long period swells (more than about 12 seconds between waves) hit the coastline at a time when there are light winds locally (and therefore small windsea).

13. Wave Speed
If the crest of an ocean wave moves a distance of 20 meters in 10 seconds, then the speed of the ocean wave is 2 m/s. On the other hand, if the crest of an ocean wave moves a distance of 25 meters in 10 seconds (the same amount of time), then the speed of this ocean wave is 2.5 m/s. The faster wave travels a greater distance in the same amount of time.

14. Progressive wave motion
This diagram shows how the wave base is deeper with longer wavelengths.

15. Seiche or Standing wave motion
These waves go up and down or “rock” and are found in semi-enclosed areas, basins, bays, harbors, or your bathtub!

17. How Tsunamis form

21. Types of Coastlines Sea Cliff

22. High Energy Beach

23. Low Energy Beach

24. TIDES
Tides are the alternating rise and fall of sea level with respect to land, as influenced by the gravitational attraction of the moon and sun.

25. Other factors influence tides; coastline configuration, local water depth, seafloor topography, winds, and weather alter the arrival times of tides, their range, and the interval between high and low water.

28. The Sun does influence our tides to some degree (the effect of the Sun on Earth tides is less than half that of the Moon).

29. Proxigean Spring Tide
When the moon, sun, and earth are all at their closest point, they are said to be at the Proxigee.
This occurs roughly every 1 ½ years.
Mass release of eggs and mating occurs during this strong tide
Our last one was just last Sunday, May 6, 2012.