Hydrosphere Contents

4. Oceans

Conclusion

The oceans contain 97% of all water on the planet. Their surface currents are driven by global wind patterns. Their deeper currents are controlled by seawater density, in turn determined by temperature and salinity. Oceans play a crucial role in influencing and regulating the Earth's climate.

Questions and answers

1.What percentage of the planet's water do the oceans contain and what percentage of the Earth's surface do they cover?

question 1 answers

2.What role do oceans play in the Earth's climate?

question 2 answers

3.Name two resource uses or exploitations of the oceans?

question 3 answers

4. Which two ions have by far the largest concentration in sea water?

question 4 answers

5. Calculate the residence time of sodium in the ocean relative to the flux from rivers. Show all workings. What processes hold oceanic sodium in steady state?

question 5 answers

6. Why are the density and radiation absorption properties of water important to ocean processes?

question 6 answers

7.What is the major wind pattern in the N. Atlantic, and why is this important to ocean water circulation?

question 7 answers

8.How is the three dimensional pattern of currents controlled below 200- 300 metres?

question 8 answers

9.Where is the 'Antarctic Bottom Water' formed?

question 9 answers

10.Why is the eventual upwelling of deep water very important biologically and economically?

question 10 answers

11.What is the cloud-algae theory?

question 11 answers

Question 1 answer

The oceans contain 97% of all water on the planet, and cover 71% of the Earth's surface reaching depths of 10,000 metres.

Question 2 answer

Ocean currents distribute energy towards the poles and influence atmospheric circulation. The regions of the land close to the sea generally have a higher rainfall and smaller annual temperature variation than areas located far inland.

Question 3 answer

Answers include: Fishing; oil reserve; other minerals in the regions of the continental shelf; dumping of many kinds of waste product.

Question 4 answer

Chloride (Cl) = 18.98% by weight
Sodium (Na) = 10.556% by weight

Question 5 answer

Residence Time = Volume of Oceanic Sodium = 1.44 x 1014 metric tonnes
Total Sodium Flux from Rivers 0.68 x 106 metric tonnes/year

Residence Time = approximately 210 million years

Removal processes balance supply processes. Sodium is
removed within the pore waters of sediments which subduct at
subduction zones. It also can be removed in those small areas
of the ocean where evaporites are forming.

Density characteristics are the principal control on the formation
of oceanic deep water. Radiation absorption is less in visible
regions, this is an important control on the depth of biological
activity (photosynthesis) in oceans.

Question 7 answer

Anticyclonic gyre with predominantly westerly winds flowing
across the North Atlantic from USA and Canada towards NW
Europe and a counter flowing easterly wind blowing back across
the Atlantic a few degrees north of the equator. Underneath
these winds there is a similar pattern of surface circulation in the
oceans i.e. the surface currents (2-300 metres) are driven by the
global wind patterns.

Question 8 answer

The 3-D pattern is controlled by the density of sea water, not by wind.

Question 9 answer

It is formed at the edge of the Antarctic continent during winter and these cold waters flow away from the polar regions.

Question 10 answer

Upwelling of cold ocean bottom water often takes place thousands of miles away from where this cold water has initially sunk to the bottom of the ocean. The upwelling brings nutrient-rich waters from the ocean depths to the surface, supporting a very rich ecosystem.

Question 11 answer

It explains a dynamic balance between marine plankton, sunlight and cloud cover, which has an important impact on the world's weather.