module 11- Ocean currents

thermohaline circulation

Movement of ocean water caused by density difference brought about by variations in temperature and salinity. As ocean water freezes at the poles it concentrates salt, and the colder, denser water sinks.

List the steps in thermohaline circulation

1: Warm water flows from the Gulf of Mexico, to the North Atlantic where some of it freezes or evaporates. 2:The remaining water, now saltier and denser, sinks to the bottom of the ocean. 3:The cold water travels along the ocean floor, connecting the world's oceans 4:The cold deep water eventually rises to the surface and circulates back to the North Atlantic. 5:Repeat

Salinity

A measure of the amount of dissolved salts in a given amount of liquid

Explain upwellings

Along the west coasts of most continents, for example, the surface currents diverge, or separate from one another, causing deeper waters to rise and replace the water that has moved away. This upward movement of water toward the surface, is called upwelling.

Explain why some regions of the ocean support highly productive ecosystems

Because of upwellings, deeper waters rise to the surface, and bring nutrients from the ocean bottom with them, thus making nutrients more accessible to the producers on the surface. These producers then support the populations that rely on them for nutrition.

What is the main difference between El Nino and La nina?

El nino causes the trade winds to be unusually weak, and might even change direction. La Nina cause them to be unusually strong

Give a specific example to further explain the previous card.

In the Northern Hemisphere, for example, the trade winds near the equator push water from the northeast to the southwest. However, the Coriolis effect deflects this wind-driven current so that water actually moves from east to west at the equator.

What are some consequences of la Nina?

It causes warmer and more humid weather in areas east due to the forceful flowing of warmer waters in that direction. The forcefulness can also encourage the formations of hurricane and tropical storms in the gulf of mexico.

Does warm water expand and rise? Or decrease in volume and sink?

It expands and rises; Just like warm air

What is the beneficial affect of thermohaline circulation?

It moves heat and nutrients, necessary sources of energy that sustain life, around the globe

What are some consequences of El Nino?

It prevent Upwelling from occurring as water is pushed west at a less forceful rate. Many fish and marine life populations rely on the nutrition provided by these upwellings, so without it growth is stunted in the areas in which the upwelling would usually occur.

Gyres

Large scale patterns of water circulation that moves clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere

Give an example of a cause of how surface water circulates

Since the tropics receive the most direct sunlight throughout the year, this makes the tropic's water warmer. Since that warm water expands and rises, this raises the water surface by about 3 inches. This volume increase causes gravity to push the water away from the equator. This effect of gravity, combined with other forces, is what causes surface water to circulate.

What is the relationship between ocean surface currents in the midlatitudes in southern and northern hemisphere

Surface currents within the midlatitudes of the northern hemisphere create a pattern that rotates clockwise. Within the southern hemisphere, surface waters in the midlatitudes rotate counterclockwise.

How do trade winds interact with the Coriolis effect when influencing surface water circulation?

The trade winds cause the surface water to be pushed in one direction. The Coriolis effect then takes that initial direction, and deflects it so that it appears to take the water on a slightly different course.

List some ways that air circulation and ocean circulation are similar

They both have the same causes: Unequal heating of the earth, trade winds, the rotation of the earth, coriolis effect, heat expansion and elevation. They both also have different layers in which air or water will travel to depending on its density, volume, or temperature.

What is a gyres purpose?

To redistribute heat in the ocean

Ocean currents are driven by----

a combination of temperature, gravity, prevailing winds, the Coriolis effect, salinity, and the locations of continents.

What is El Nino?

an irregularly occurring and complex series of climatic changes affecting the equatorial Pacific region and beyond every 3-5 years, characterized by the appearance of unusually warm, nutrient-poor water off northern Peru and Ecuador, typically in late December.

Given an example of a current that affects temperatures on the coasts of a continent

he California Current, which flows south from the North Pacific along the coast of California, causes coastal areas of California to have cooler temperatures than areas at similar latitudes on the east coast of the United States. Similarly, warm water from the tropics moves along the east coasts of continents, and the warm air immediately above these waters causes warmer temperatures on land.

How does salinity affect the density of water?

higher salinity then higher density, which causes the water to be heavier and to sink

How does the flow of ocean water affect climates around the globe?

it moves warm and cold waters to different parts of the globe

What drives thermohaline circulation?

surface waters that contain unusually large amounts of salt, and thus are more dense and sink to the bottom of the ocean.

What is the name of the ocean circulation current that drives the mixing of surface water and deep water

thermohaline circulation

List some ways that air circulation and ocean circulation are different

water has the added element of salt, which complicates water's density and thus interferes with its elevation. Ocean currents also have marine life that resides inside of it at all times, and thus has more nutrients to spread in order to sustain this life.