1. Chapter 15
Section - 1

2. Factors that Influence Ocean Currents
Ocean currents are masses of ocean water that flow from one place to another
surface currents develop from friction between the ocean and the wind that blows across its surface
some currents are short- lived and affect only small areas
these are a response to local/seasonal influences
other currents are relatively permanent that extend over long areas of the oceans
the major horizontal movements of surface water is closely related to the general circulation pattern of the atmosphere

3. Ocean Circulation Patterns
Gyre = the large circular surface current pattern found in each ocean
eg, North Pacific Gyre
the center of each gyre coincides with the subtopics at about 30 degrees North or South latitude, so they are often called subtropical gyres
there is a correspondence between the direction of surface- current flow and the major wind belts of the world
subtropical gyres rotate clockwise in the Northern Hemisphere, and counterclockwise in the Southern Hemisphere
this is because wind generates surface currents, as well as...
the Coriolis Effect
the deflective force of Earth's rotation on all free- moving objects, including the atmosphere and oceans
there are four main currents within each gyre
if an object is dropped into a gyre it would take about six years to go completely around
when the North Atlantic Current goes towards Western Europe, it splits and carries warm weather to the otherwise cold area

5. More Ocean Circulation Patterns
the circular motion of gyres leaves a large central area that has no well-defined currents
in the North Atlantic, this zone of calmer waters is known as the Sargasso Sea, named for large amounts of Sargassum, a type of floating seaweed
Indian Ocean is influenced by summer and winter monsoons
when the winds change direction, the surface currents also change direction

6. Ocean Currents of the World

7. Ocean currents Ocean currents
Warm currents- move from low to high latitudes (move heat from warmer to cooler areas)
North American current keeps Great Britain and western Europe warmer than would be expected based on their latitude
Cold currents- move from high to low latitudes( moderate temperatures in tropics and mid-latitudes)
Benguela Current (western Africa), Peru Current, California Current
Cause fogs and droughts/deserts along the west coast of continents ( Atacama, Namib)
Maintain Earth’s heat balance- ¼ heat transported from tropics to poles is transported by water, the rest is by wind

8. Peru Current
"GS103 - Lecture Outlines Sp08." GS103 - Lecture Outlines Sp08. Web. 22 May <

9. Upwelling
Upwelling is the rising of cold water from layers below the surface.
Induced by wind
Brings nutrient rich water to the surface
Supports marine organisms
Most common on west coasts
Most distinguished: California, Western South America, and West Africa
Cause of upwelling
Coastal winds and Coriolis effect cause surface water to move away from the shore

10. Upwelling Cause of upwelling
Cold water from below replaces warmer surface water
Results in lower surface temperatures
For example, Atlantic temperatures in August are 21°C or higher and Pacific temperatures are 15°C

11. Deep-ocean Circulation
Deep ocean Circulation is governed by gravity and driven by density differences
- Density differences are caused by temperature and salinity differences. Because of this Deep-ocean circulation is often also called thermohaline circulation.
-Density differences cause denser water to sink and slowly spread out beneath the surface

12. Deep-Ocean Circulation
Deep-ocean currents
-Deep-ocean currents are created when the water involved with thermohaline circulation begins in high latitudes at the surface and then sinks.
-The water at high latitudes was there because the salinity, the amount of salt in the water, of the cold water increased due to sea-ice formation.

13. Thermohaline Circulation
Thermohaline Circulation Photograph. N.p

14. Various Components of the Coastal Zone
Shorelines Are Dynamic-
topography
geologic makeup
climate
Shore- area that extends between the lowest tide level and the highest elevation on land that is affected by storm waves
Shore is divided into two parts-
Foreshore-area exposed when the tide is out and submerged when the tides in
Backshore-landward of the high tide shoreline. Usually dry, being affected by waves only during storms
Two other zones-
Nearshore Zone-lies between the low tide shoreline and the line where waves break at low tide
Offshore Zone-seaward of the nearshore
Shoreline- line that marks the contact between land and sea

15. Various Components of the Coastal Zone
Coast-extends inland from the shore as far as ocean related features can be found
Coastline-marks the coast's seaward edge, whereas the inland boundary is not always obvious or easy to determine