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Ocean Currents – Video Lesson
Directions: Go to the website, http://www.montereyinstitute.org/noaa/lesson08.html to view a video lesson on ocean currents. Follow along the video to answer the questions below.
Is the northeast United States affected by the Gulf Stream? Why or Why Not?
The Gulf Stream Current, which shows up in this temperature coded satellite image as a broad dark orange swath, has followed this course through the North Atlantic for millennia
What are eddy currents?
eddy currents that spin off the Gulf Stream die out within a few months
What are the three main causes of currents?
Currents are caused by winds, gravity, and variations in water density in different parts of the ocean
What are the two current systems?
There are two distinct current systems in the oceans–surface circulation, which stirs a relatively thin upper layer of the sea, and deep circulation, which sweeps along the deep-sea floor
What is a gyre? How many major gyres are on the Earth?
the gyre–a well-organized, roughly circular flow
Five enormous gyres spin in subtropical waters, two in both the Atlantic and Pacific Oceans, and one in the Indian Ocean. Smaller polar gyres stir the northern Atlantic and Pacific. One surface current circles endlessly around Antarctica
What is the most important cause of surface currents?
Wind is the most important cause of surface currents
Why does the Coriolis Effect occur?
The Coriolis Effect occurs because the earth's surface rotates faster at the equator than at the poles.
What parts of the Earth does the Coriolis Effect (solid earth, oceans, atmosphere)?
It influences the paths of moving objects that are only loosely in contact with the ground, from currents to winds to airplanes… ocean/ atmosphere
What are the directions of deflection due to the Coriolis Effect in the Northern and Southern Hemispheres?
The Coriolis deflection is to the right in the northern hemisphere, and to the left in the southern hemisphere
What role does land play in affecting surface currents?
When a current runs into a continent, it must turn aside
How long does water take to complete the entire gyre in the Atlantic Ocean?
A single trip around this circuit takes about 10 years.
What are longshore currents? How can they affect beaches?
Longshore currents are temporary and flow along coastlines when waves run into the shore at an angle
They bulldoze great volumes of sand along the shore, causing beaches to disappear and harbors to fill in
What are rip currents? How can they affect swimmers at beaches?
.Rip currents are temporary currents that form where obstacles channel water away from the shoreline
Many an unwary swimmer and beachcomber has been swept out to sea after stumbling into a rip
What are upwelling currents? How do they influence life forms in coastal areas?
Upwelling occurs when winds push surface water away from the shore, and deeper water rises to fill the gap.
These cold currents bring nutrients to the surface and stimulate high plant and animal productivity
What is the global conveyor belt?
Deep currents twist together into a continuous stream that loops through all the oceans, called the global conveyer belt.
How long does one cycle through the global conveyor belt last?
over the course of 1,000 years
What drives the global conveyor belt?
This vast, global circulation is driven by density variations in the ocean. Sometimes called thermohaline circulation because it depends on temperature and salinity
In what regions does the global conveyor belt begin?
The conveyer belt begins at the surface of the North Atlantic where great amounts of water cool and sink off the coast of Greenland.
What happens as the global conveyor belt begins to heat up?
these currents warm up and become less and less dense as they travel, enough that they eventually rise back toward the surface
What happens to the heated portions of the global conveyor belt, allowing the process to repeat itself?
Drawn by the inexorable pull of the conveyer belt, these now warm waters loop back the way they came and eventually return to the North Atlantic to begin the long journey all over again.
Ocean Currents – Video Lesson Part 2
Directions: Go to the website, http://www.montereyinstitute.org/noaa/lesson08.html. CLICK ON THE GLOBAL IMPACT TAB. Then, follow along with the video to answer the questions below.
1. What is upwelling?
Upwelling, the rise of deeper water to the surface
2. In what % of the earth’s oceans does upwelling occur? What % of the world’s fishing industry occurs in upwelling regions?
occurs only on 10% of the ocean
that small area makes up half of the world's fisheries
3. What type of seawater is brought to the surface during upwelling?
The cool, nutrient-filled water in upwelling currents support blooms of algae and seaweed, the base of the food chain for many clams, crustaceans, and fish
4. What three types of fish are found almost entirely in upwelling regions?
Herring, anchovy, and sardines, three of the most widely harvested fish, are especially concentrated in upwelling zones
5. How do currents in general affect earth’s climate?
Overall, ocean currents moderate the planet's temperature extremes
6. How do western boundary currents affect climate?
Warm flows, like the western boundary currents, carry heat from the tropics toward the poles
7. How do eastern boundary currents affect climate?
Cold flows, such as the eastern boundary currents, bring cooler temperatures to low latitudes
8. Specifically, how is the climate of Western Europe and northern Canada (equal latitudes) affected by currents?
Because Western Europe is bathed in warm waters and winds coming east across the Atlantic, its climate is much warmer and milder than other areas at the same latitude, such as northern Canada and Alaska
9. How might global warming affect the North Atlantic? What would happen to the global conveyor belt?
global warming could severely alter current patterns
and significant melting of glacial and sea ice, a layer of warm fresh water could form at the sea surface. This layer could block the formation and sinking of cold salty water there, and turn off the global conveyer belt.
10. How much could temperatures in Western Europe decrease if this were to occur?
its northward pull on warm surface currents, shuts down, average temperatures in much of Europe would plunge 10-20° F
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