W6: Motion In The Ocean/Ocean Conveyer Belt

This water moves sluggishly southward until it joins a similar mass called the _________ ______ _____. Here, the conveyor splits in two, with one branch circling Antarctica and then moving on to the ocean south of Australia, and the other branch heading north, up the east coast of Africa.

*Antarctic Bottom Water*

Together, they pass the ____ __ ____ ____ and head north, past the west coast of Africa and Europe, toward Iceland in the North Atlantic, where the 1,000-year journey begins again.

*Cape of Good Hope*

*________* are cohesive streams of seawater that circulate through the oceans. Some are short-lived and small, while others are vast flows that take centuries to complete a circuit of the globe.

*Currents*

*Global Impact*

*Influence or effects upon Earth as a whole system.*

A much colder flow called the *________* Current travels along the west side of Greenland. This current is notorious for flushing icebergs, including the one that sank the Titanic, into the heavily traveled North Atlantic shipping lanes.

*Labrador*

*Colder and saltier, this dense water begins to sink. Warm water from the tropics moves in to replace it at the surface, and it, too, begins to cool. The cold water descends to the ocean bottom where it forms what oceanographers call the _____ ________ ____ _____, a mass of water that fills most of the deep Atlantic basin.*

*North Atlantic Deep Water*

On the other side of the gyre, winds known as the westerlies, combined with the Coriolis deflection, push mid-latitude water to the east. Called the *_____ _________* Current, this flow loses heat to the atmosphere.

*North Atlantic*

The sinking and rising of ocean water on a grand scale is referred to as...

*The Great Ocean Conveyer Belt*

*___ ____ ______* is the strongest, deepest, and fastest part of the gyre, and it transports an enormous amount of heat toward the poles.*

*The Gulf Stream*

*_____* is the most important cause of surface currents. When strong, sustained ____s blow across the sea, friction drags a thin layer of water into motion.

*Wind*

The Great Ocean Conveyer Belts affects the Earth's *_______* by driving warm water from the ocean at the equator, and cold water from the poles around the Earth.

*climate*

Hemmed in by the continents, this new deep water of the *_______ ____* can only flow south, past the equator, all the way to the far ends of Africa and South America. As the current travels around the edge of Antarctica, fresh streams of cold water sink into and recharge the *_______ ____.*

*conveyer belt*

When objects move toward higher, slower moving latitudes, they outpace the rotation of the surface, and seem to veer toward the *____.*

*east*

If there is more rainfall in the North Atlantic, and significant melting of _______ ___ ___ ___, 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.

*glacial and sea ice*

*Currents are surprisingly important to landlocked creatures like us as well because they partially regulate the ______ _______ and govern the productivity of fishing grounds.*

*global climate*

Surface currents are also triggered by _______. The top of the sea is not flat but has broad hills and valleys.

*gravity*

The dominant pattern of surface circulation is the ____ -a well-organized, roughly circular flow.

*gyre*

The movements of currents are also constrained by the shape of the *_____ _______*. When a current runs into a continent, it must turn aside.

*ocean basins*

*The unequal distribution of solar _________ on Earth's surface is one of the most important factors in the thermohaline conveyor's circulation.*

*radiation*

Thermo means heat, and "haline" refers to...

*salinity*

The movement of ocean water is readily observable in the rise and fall of *___ _____* and the continual lapping of waves along the coastlines of continents and islands.

*the tides*

The *_____* winds start a current that is turned by the Coriolis Effect into a westward flow along the equator. The Equatorial Current gets warmer and warmer as it travels across the tropics.

*trade*

Cool, nutrient-filled water in *__________* currents support blooms of algae and seaweed, the base of the food chain for many clams, crustaceans, and fish. Herring, anchovy, and sardines, three of the most widely harvested fish, are especially concentrated in *__________* zones.

*upwelling*

Other currents are temporary-longshore, rip, and upwelling currents only run in certain seasons or *_______* conditions.

*weather*

*With a volume more than 16 times the combined flow of all the _______ ______, the conveyer belt slowly but steadily empties one ocean into another, and over the course of 1,000 years, turns the water in them upside down.*

*world's rivers*

The Gulf Stream

-A warm ocean current that flows from the Gulf of Mexico northward through the Atlantic Ocean. -*The heat it releases helps to keep northwest Europe warmer than other regions at the same latitude.*

The Great Ocean Conveyer Belt

-An interconnected system of ocean currents that link the Pacific, Indian, and Atlantic oceans. -A constantly moving system of deep-ocean circulation driven by temperature and salinity.

Thermohaline

-An oceanic circulation pattern that drives the mixing of surface water and deep water. -Warm saltwater large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes.

*The Coriolis Effect*

-The effect of Earth's rotation on the direction of winds and currents. -Occurs because the earth's surface rotates faster at the equator than at the poles. -Influences the paths of moving objects that are only loosely in contact with the ground, from currents to winds to airplanes.

The Sea near The Poles

-The water gets very cold, chilled by low air temperatures to freezing and below. -Polar seawater also gets saltier, because when sea ice forms, the salt is left behind. -As seawater gets colder and saltier, its density increases, and it starts to sink toward the bottom. -Surface water is pulled in to replace the sinking water, and in its turn, eventually becomes cold and salty enough to sink. Thus, a current begins.

*Thermohaline Circulation (THC)*

-Water circulation produced by differences in temperature and/or salinity (and therefore density). -A part of the large-scale ocean circulation that is driven by global density gradients created by surface heat and freshwater fluxes.

It takes water almost _____ _____ to move through the whole conveyor belt.

1,000 years

There are two distinct current systems in the oceans. What are they?

1. Surface circulation. 2. Deep circulation.

*From the first video, what are the 4 "factors that put the motion in the ocean?"*

1. Tides. 2. Wind. 3. Heat. 4. Salinity.

Once the conveyer belt and its northward pull on warm surface currents shuts down, average temperatures in much of Europe would plunge by how much?

10-20 degrees Fahrenheit

El Nino

A warm ocean current that flows along the coast of Peru every seven to fourteen years.

Winds and gravity start water moving, but the currents that form don't flow parallel to the wind or straight down the steepest surface. Instead, the currents move at an angle to the force that generates them-a phenomenon called the _________ effect.

Coriolis

The very warm Equatorial ______________, which flows eastward, can help trigger the unusual weather pattern called El Nino.

Countercurrent

____ ___________ sweeps along the deep-sea floor.

Deep circulation

Thermohaline Currents

Deep, slow-moving currents driven by the density difference in the ocean water.

The conveyer belt begins at the surface of the North Atlantic where great amounts of water cool and sink off the coast of *_________.*

Greenland

________ ___________ stirs a relatively thin upper layer of the sea.

Surface circulation

Upwelling

The movement of deep, cold, and nutrient-rich water to the surface.

Where are the ocean gyres located?

There are 5 enormous gyres in subtropical waters, 2 in both the Atlantic and Pacific oceans, and 1 in the Indian Ocean. Ocean. Smaller polar gyres stir the northern Atlantic and Pacific. One surface current circles endlessly around Antarctica.

True or False: Cold, salty water is dense and sinks to the bottom of the ocean.

True

True or False: It is possible that global warming could severely alter current patterns, at least in the short term.

True

True or False: Many scientists consider the thermohaline conveyor essential to a healthy ocean ecosystem and to the stability of Earth's climate.

True

The Equatorial Current

Westward flowing currents that travel along the equator in all ocean basins, caused by trade winds.

The currents that influence/make up a gyre are controlled by what?

Winds and gravity, and they're steered by the placement of the continents and the rotation of the Earth.

The eastern and western currents of the gyre begin where the equatorial and mid- latitude currents are ________ by land.

blocked

Unlike many other causes of _______ ______, catastrophic cooling due to the loss of the global conveyer belt could be quite rapid, taking just a few years or decades.

climate change

*Longshore currents* flow along __________ 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.

coastlines

The formation of sea ice at high latitudes also affects the density of water. As ice forms at the ocean surface, salt ions are left behind, increasing their concentration in the liquid water below. Because salt ions have more mass than water molecules, any increase in their _____________ increases the solution's density.

concentration

Where currents converge or run into a _________, water piles up.

continent

*Deep-water circulation has a scale, pace, and power very different from surface circulation. Deep currents twist together into a continuous stream that loops through all the oceans, called the global ______ ____.*

conveyer belt

The complex interplay between wind, gravity, Coriolis Effect, and topography determines the location, size, shape, and direction of the surface _______ _____.

current gyres

The Coriolis __________ is to the right in the northern hemisphere, and to the left in the southern hemisphere.

deflection

Two sections of the conveyer belt split off and turn northward, one into the Indian Ocean, the other into the Pacific. Both these currents warm up and become less and less _____ as they travel, enough that they eventually rise back toward the surface. 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.

dense

The changes in heat and salt content constantly affects the _______ of the ocean.

density

Finally, the slow and very shallow Canary Current runs south along the eastern edge of the Atlantic, carrying cold water to the *________* to complete the gyre. A single trip around this circuit takes about 10 years.

equator

Currents are caused by winds, _______, and variations in water density in different parts of the ocean.

gravity

Upwelling, the rise of deeper water to the surface, occurs only on 10% of the ocean. But that small area makes up _____ of the world's fisheries.

half

Warm flows, like the western boundary currents, carry heat from the tropics toward the poles. Cold flows, such as the eastern boundary currents, bring cooler temperatures to low __________.

latitudes

Currents are an integral and dynamic part of the world's oceans-they help determine the characteristics and behavior of seawater, and the distribution and abundance of ______ life.

marine

Many surface currents - the ones with names - have been in constant motion for _________.

millennia

Currents play an important role in the Earth's climate system. Overall, ocean currents ________ the planet's temperature extremes.

moderate

In the Indian Ocean, water warms and rises to the surface, where it warms even more and provides moisture for ________ rains. This warm water then swings back and joins the other surface currents flowing in from the Pacific.

monsoon

Water moving __________ in the conveyor cools, and as a result it becomes denser than the warmer water arriving from the tropics behind it.

northward

The network of currents that constantly circulates ocean water from one side of the globe to another is less ___________.

noticeable

*Upwelling* occurs when winds push surface water away from the shore, and deeper water rises to fill the gap. These cold currents bring _________ to the surface and stimulate high plant and animal productivity.

nutrients

Known as the thermohaline conveyor, this conveyor belt circulates ocean water around the globe, and in the process _____________ heat and nutrients.

redistributes

When objects move toward lower, faster moving latitudes, they lag behind the *_________* of the surface.

rotation

*Rip currents* form where obstacles channel water away from the _________. Many an unwary swimmer and beachcomber has been swept out to sea after stumbling into a rip.

shoreline

The major ocean gyres circle around a low mound a meter or so high. In summer, intense sunlight can heat and expand seawater, raising the _______ by several centimeters in the tropics.

surface

Sometimes called ____________ circulation because it depends on temperature and salinity, the conveyer begins on the surface of the sea near the poles.

thermohaline

The Sun warms surface water near the equator. This warm water then moves as a current from the ________ toward higher latitudes, where it cools and transfers its heat to the atmosphere.

tropics

Because Westerm Europe is bathed in warm waters and winds coming east across the Atlantic, its climate is much _______ and milder than other areas at the same latitude, such as northern Canada and Alaska.

warmer

The movement of the very topmost layer of the sea pulls on the water just beneath, which then in turn starts the layer under it moving. Energy from the wind is quickly dissipated, so ____-______ ________ slow down with depth, and finally die out within a few hundred meters of the surface.

wind-driven currents