Climate effects

One of the most dramatic forms of weather occurs over the oceans: tropical cyclones (also called “typhoons” and “hurricanes” depending upon where the system forms). Ocean currents greatly affect the Earth’s climate by transferring warm or cold air and precipitation to coastal regions, where they may be carried inland by winds. The Antarctic Circumpolar Current encircles that continent, influencing the area’s climate and connecting currents in several oceans.

III. Answer the questions:

1. What is oceanography?

2. How does the ocean and atmosphere link?

3. How many per cents of the Earth’s surface are covered by ocean?

4. What is the average salinity of the ocean?

5. What is the World Ocean?

6. How many oceans are there on the Earth?

7. Is the Great Salt Lake a part of the ocean? Why?

8. The Pacific Ocean is the largest ocean in the world, is not it? What are the others?

9. What is the deepest place in the ocean?

10. What is the reason of the blue color of the ocean water?

11. What is the ocean glow?

12. How many oceanic zones do you know? Make a list of them and give their brief description.

13. How do the oceans affect the climate of the Earth?

IV. Do you agree or disagree with the following statements? Prove your opinion.

1. Oceanography covers a wide range of topics, including marine organisms and ecosystem dynamics; ocean currents, waves, and geophysical fluid dynamics; plate tectonics and the geology of the sea floor; and fluxes of various chemical substances and physical properties within the ocean and across its boundaries.

2. An ocean is a major body of fresh water, and a principal component of the hydrosphere.

3. There is only one ocean on our planet.

4. The Indian Ocean is the largest and deepest ocean on the Earth.

5. The oceans cover ¾ of the earth’s surface and have great impact on the biosphere.

6. Oceanic crust is the thin layer of solidified volcanic basalt that covers the Earth’s mantle where there are no continents.

7. Ocean water has blue color because it reflects the color of the sky.

8. Ocean does not have any glow.

9. Ocean is not divided into regions.

10. One of the most dramatic forms of weather phenomena occurs over the oceans: tropical cyclones.

V. Describe the oceanic divisions using the picture on page 32.

VI. Is there an ocean in our region? Describe it.

VII. What new information have you learned from this article? Have you got anything to add? Discuss it into groups.

Ocean current

Major ocean surface currents. Noaa map.

I. Learn active vocabulary:

contour – очертание, контур, характер

volume flow rate – объемная скорость течения, объемный расход

swift - быстрый

to empty - вливаться

brine – морская вода

exclusion – за исключением

ocean current – океанское течение

II. Read and translate the text:

An ocean current is continuous, directed movement of ocean water. Ocean currents are rivers of hot or cold water within the ocean. The currents are generated from the forces acting upon the water like the planet rotation, the wind, the temperature and salinity differences and the gravitation of the moon. The depth contours, the shoreline and other currents influence the current’s direction and strength.

Important currents

Ocean currents can flow for thousands of kilometers. They are very important in determining the climates of the continents, especially those regions bordering on the ocean. Perhaps the most striking example is the Gulf Stream, which makes northwest Europe much more temperate than any other region at the same latitude. Another example is the Hawaiian Islands, where the climate is cooler (sub-tropical) than the tropical latitudes in which they are located because of the California Current.

Background

Surface ocean currents are generally wind driven and develop their typical clockwise spirals in the northern hemisphere and counter-clockwise rotation in the southern hemisphere because of the imposed wind stresses. In wind driven currents, the Ekman spiral effect results in the currents flowing at an angle to the driving winds. The areas of surface ocean currents move somewhat with the seasons; this is most notable in equatorial currents.

Deep ocean currents are driven by density and temperature gradients. Thermohaline circulation, also known as the ocean’s conveyor belt, refers to the deep ocean density-driven ocean basin currents. These currents, which flow under the surface of the ocean and are thus hidden from immediate detection, are called submarine rivers. These are currently being researched by a fleet of underwater robots called Argo. Upwelling and downwelling areas in the oceans are areas where significant vertical movement of ocean water is observed.

Surface currents make up about 10% of all the water in the ocean. Surface currents are generally restricted to the upper 400 meters of the ocean. The movement of deep water in the ocean basins is by density driven forces and gravity. The density difference is a function of different temperatures and salinity. Deep waters sink into the deep ocean basins at high latitudes where the temperatures are cold enough to cause the density to increase. The main causes of currents are: solar heating, winds and gravity.

Ocean currents are measured in Sverdrup with the symbol Sv, where 1 Sv is equivalent to a volume flow rate of 106 cubic meters per second.