1. Tuesday April 5, 2011
(The Gulf Stream; Importance of Surface Currents; Deep Ocean Circulation)

2. Give a brief description of the surface currents in Earth’s oceans.
The Launch Pad
Tuesday, 4/5/11
Give a brief description of the surface currents in Earth’s oceans.
There are five main gyres in Earth’s oceans caused by prevailing winds. The two gyres in the Northern Hemisphere rotate clockwise. The three Southern Hemisphere gyres rotate counter-clockwise. The currents of the oceans are caused by a combination of these gyre movements. Warm and cold currents have a huge effect on the Earth’s climate.

3. Announcements
Test Friday!

4. Assignments For This Six-Weeks Date Issued Date Due
Video Quiz - Lakes, Rivers, and Other Water Sources
2/27
WS - Running Water and Groundwater (Part 1)
2/25
3/4
PowerPoint Project – Rivers (P5 only)
2/28
3/3
WS - Running Water and Groundwater (Part 2)
3/2
3/9
Video Quiz - Groundwater
Cornell Notes - Ice
3/8
WS - Ice
3/25
Test 8
3/11
Video Quiz – Ocean’s – Earth’s Last Frontier
3/23
Cornell Notes – Intro to Oceanography
4/4
Lab Exercise – Introduction to Oceanography
3/28
4/1
Cornell Notes – The Dynamic Ocean ??

5. Continue Cornell Notes
The Dynamic Ocean

6. Four Main Currents Exist Within Each Gyre

7. Surface Circulation
Gyres are caused by the Coriolis Effect, an apparent deflection of moving objects caused by the rotation of the earth and the inertia of the mass experiencing the effect.
The Coriolis force is quite small, and its effects generally become noticeable only for motions occurring over large distances and long periods of time, such as large-scale movement of air in the atmosphere or water in the ocean.
This force causes moving objects on the surface of the Earth to appear to veer to the right in the northern hemisphere, and to the left in the southern.
Surface currents are extremely important to Earth’s climate, as they transfer warmer water from low latitudes into higher latitudes, and thereby move heat from warmer to cooler areas.

8. This false-color satellite image shows sea-surface temperatures of the Gulf Stream. Warmer waters are shown in red and orange, colder waters in green, blue, and purple. As the Gulf Stream meanders northward, some of its branches pinch off to form large, circular eddies.
The Gulf Stream

9. Importance of Surface Currents
Ocean currents have a significant influence on climate.
When currents from low-latitude regions move to higher latitudes, they transfer heat from warmer to cooler areas on Earth.
This is how the Gulf Stream keeps Great Britain and northwestern Europe warmer during the winter than should be expected for their latitudes.
On the other hand, as cold currents originating in cold, high-latitude regions travel toward the equator, they tend to moderate the warm temperatures of adjacent land areas.
For example, the cool Benguela current off the western coast of southern Africa moderates the heat along this coast.

10. Importance of Surface Currents
Winds can also cause vertical water movements.
Upwelling is the rising of cold waters from deeper layers to replace warmer surface water.
Upwelling is most characteristic along the western coasts of continents where winds blow toward the equator and parallel to the coast.
These winds combined with the Coriolis effect cause surface waters to move away from the shore, being replaced by cooler water “upwelling” from below.
This process brings greater concentrations of dissolved nutrients to the ocean surface.

11. Deep Ocean Circulation
Circulation in the deeper ocean is a response to density differences of water at varying depths.
Recall that two factors create a dense mass of water: cold water and increased salinity.
Deep-ocean circulation is referred to as thermohaline circulation.
Most water involved in deep-ocean currents begins in high latitudes at the surface
A simplified model of ocean circulation is similar to a conveyor belt that travels from the Atlantic Ocean, through the Indian and Pacific Oceans, and back again

12. Begin Lab Exercise
Waves and Currents