1. Why is this rubber duckie on the beach?

2. In January 1992 28,000 rubber duckies were lost at sea
In January ,000 rubber duckies were lost at sea. What can their journey teach us?
Duckies have been found in Hawaii, Alaska, S. America, Scotland, Washington state
and Australia as of 2012.

3. They have revolutionized our understanding of ocean currents !
We learned that it takes 3 years to complete one circuit of the North Pacific Gyre

4. Ch. 24 The Moving Ocean

5. 24.1 Surface Currents flow in the upper 1,000 meters of ocean
driven by global winds
N. and S. hemispheres each have two circulations
caused by the Coriolis Effect
clockwise in N. hemisphere
counterclockwise in S. hemisphere

6. Current Temperature cold currents- move towards the Equator
Eastern sides of ocean basins
warm currents- move towards poles
Western sides of ocean basins
Relationship between temperature and direction of flow.

7. Currents & Winds 2 sets of global winds drive currents
Trade winds- blow from NE in N. hemisphere; SE in S. hemisphere
Westerlies- blow from SW in N. hemisphere; NW in S. hemisphere
Earth’s rotation & continents push currents along path of travel
Predict the direction of hurricane winds along the east coast of North America
Winds
Currents

8. Important Currents to Know
Gulf Stream
N. Atlantic
Canary
N. Equatorial
California
Labrador
West Wind Drift

9. Countercurrents flow in opposite direction of wind-related currents
return water taken away from one side of the ocean basin to the opposite side
EX: Equatorial Countercurrents

10. Would you expect the water off the Pacific coast of the U. S
Would you expect the water off the Pacific coast of the U.S. to be warmer or colder than off the Atlantic Coast at the same latitude?

11. 24.2 Currents Under the Surface
driven by gravity & differences in density
Density current= heavier & denser than surrounding water
Sink to bottom from surface
move very slowly
Circulate for years

12. Global Conveyor Belt global circulation of deep ocean currents
transports warm water to colder areas & cold water to warmer areas
efficient heat-transport system drives Earth’s climate!!

13. Ocean Conveyor Belt drives the Earth’s climate!
Global Conveyor Belt the transferring of heat energy from the atmosphere to the hydrosphere and back!
Ocean Conveyor Belt drives the Earth’s climate!

14. Importance of Density Currents
carry oxygen absorbed from surface for deep sea life
retain same temperature, salinity, & density as surface
turbidity currents are an example of VERTICAL density currents!

15. Density Currents from Polar Water
polar water is the most dense because it’s cold
when water freezes, it leaves behind salt
both of these factors increase density
depth of a water mass or current depends on its density

16. Density Currents from Evaporation
increased evaporation leaves salt behind, which increases the density
dense water sinks and is replaced with less dense water
Example: Mediterranean

17. Upwelling
vertical density currents that occur when cold deep water comes to the surface
can occur anywhere, prevalent along western coasts of continents

18. Two Causes of Upwelling
surface winds push water away from continent
denser, salty water suddenly sinks

19. Benefits of Upwelling large amounts of nutrients come to surface
phytoplankton populations cultivate and provide food for marine life
Large-scale fishing areas
Examples: California, Morocco, southwestern Africa, Peru, western Australia

20. 24.3 TIDES twice-daily rise and fall of Earth’s oceans
result of gravitational pulls from moon and sun
reach different levels depending on Earth’s location in relation to moon and sun
Moon has a greater effect since it is closer
The closer an object is to another the greater the gravitational pull.
The sun’s influence is about ½ of that of the moon’s.

21. 24.3 TIDES Moon’s effect on the tides:
The moon orbits around Earth causes bulges to rotate around the Earth over the lunar month (~29 days).
The moon rises about 50 minutes later each days so do the tides.
Uniform water level
Moon
Moon’s orbit
Low tide
Direct high tide
Indirect high tide

22. 24.3 TIDES sun can enhance or detract from the moon’s effects
Spring Tides occur when the sun and moon are in alignment (enhances tides)
High tides are higher and low tides are lower

23. 24.3 TIDES
Neap Tides occur when the sun and moon are at right angle (sun detracts from moon’s pull)
High tides are not as high and low tides are not as low

24. Another factor adding to the tidal effect is the moon’s proximity to the earth: perigee apogee

25. 24.3 TIDES Tidal Range is the difference between high and low tides.
more noticeable on oceans than lakes
Small lakes show no tides at all
Great Lakes have tides with ranges of just a few centimeters
Ocean tidal ranges can vary greatly
closer to the poles the greater the tidal range

26. 24.3 TIDES
The shapes of individual shorelines influence the tidal range
A narrow bay has a greater tidal range than a wide coastal area.
Bay of Fundy, High tide
Bay of Fundy, Low tide