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Unit 4 The importance of oceans. Unit 4. The importance of oceans. Unit 4 The importance of oceans. Where are the major oceans and seas?. 361 million km² of the earth’s surface is covered by water. Unit 4 The importance of oceans. Where are the major oceans and seas?. - PowerPoint PPT Presentation
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Where are the major oceans and seas?Where are the major oceans and seas?
361 million km² of the earth’s surface is covered by water.
Unit 4 The importance of oceans
Where are the major oceans and seas?Where are the major oceans and seas?Unit 4 The importance of oceans
Oceans and seas occupy 71% of the earth’s surface.
Oceans and seas occupy 71% of the earth’s surface.Oceans are unevenly distributed over the earth’s surface. Most of the southern hemisphere is covered by oceans.
Oceans are unevenly distributed over the earth’s surface. Most of the southern hemisphere is covered by oceans.The four oceans are the Pacific, the Atlantic, the Indian and the Arctic.
The four oceans are the Pacific, the Atlantic, the Indian and the Arctic.
Where are the major oceans and seas?Where are the major oceans and seas?Unit 4 The importance of oceans
km
Pacific Ocean
Atlantic Ocean
Indian Ocean
Arctic Ocean
Baltic Sea
North Sea
Mediterranean Sea
Black Sea
Caspian Sea
Red Sea Arabian Sea
The Gulf
Bay of Bengal
South China Sea
East China Sea
Yellow Sea
Sea of Japan
Sea of Okhotsk Hudson Bay
Gulf of Mexico
Caribbean Sea
°N
°N
°S
N
°
Pacific OceanPacific OceanPacific Ocean is the largest and deepest of the world’s
four oceans, covering more than a third of the earth’s surface.
The size of the Pacific Ocean is 165 000 000km², which is bounded on the east by the North and South American continents; on the north by Bering Strait; on the west by Asia; and on the south by Antarctica.
The average depth of the ocean is about 4 282 m and the greatest depth is 11 033 m in the Mariana Trench.
Much of the plant and animal life of the Pacific Ocean is concentrated along its margins.
Unit 4 The importance of oceans
Atlantic OceanAtlantic OceanAtlantic Ocean is the second largest of the earth’s four
oceans and the most heavily travelled.
The Atlantic Ocean has a surface area of 82 000 000
km².
The Atlantic Ocean is an “S-shaped” north-south
channel, extending from the Arctic Ocean in the north to the Antarctic continent in the south. It is situated between the western coast of the American continents and the eastern coasts of Europe and Africa.
The Atlantic Ocean has an average depth of 3 926 m.
The greatest depth is 8 742 m in the Puerto Rico Trench.
Unit 4 The importance of oceans
Indian OceanIndian OceanIndian Ocean is the third largest of the earth’s
four oceans, bounded on the west by Africa, on the north by Asia, on the east by Australia, and on the south by Antarctica.
The total area of the Indian Ocean is 73 400 000 km². The average depth is 4 210 m and the deepest point is 7 725 m, off the southern coast of the Indonesian island of Java.
The Indian Ocean contains numerous islands, the largest of which are Madagascar and Sri Lanka.
Tropical storms occur occasionally and the ocean is notable for seasonal winds called monsoons.
Unit 4 The importance of oceans
Arctic OceanArctic OceanArctic Ocean is the smallest of the four world oceans.
The Arctic Ocean extends south from the North Pole to the shores of Europe, Asia and North America.
The total surface area of the Arctic Ocean is 14 000 000 km². The average depth is 1 500 m and the deepest point in the Arctic Ocean is 5 450 m in the Pole Abyssal Plain near the North Pole.
Sea ice is formed by the freezing of seawater which is the most extensive form of ice in the Arctic Ocean.
In winter a permanent cap of sea ice covers all of the
ocean surface.
Unit 4 The importance of oceans
Why are oceans important?Why are oceans important?Recreation
Most of us are familiar with our beaches and seas as these are places for recreation.
Unit 4 The importance of oceans
We go there for swimming in the hot summer season. They are also places for surfing, sailing and fishing.
Why are oceans important?Why are oceans important?Trade and shipping
Oceans have been used for transporting raw materials and manufactured products.
Sea transport is the cheapest way of sending products in large quantity over a long distance.
Unit 4 The importance of oceans
Why are oceans important?Why are oceans important?Trade and shipping
Shipping routes link up industrial and densely populated regions in the world.
Oceans are important as over 70% of world trade is carried out by ships.
Unit 4 The importance of oceans
Major sea routes of the worldMajor sea routes of the worldUnit 4 The importance of oceans
°N
°N
°S
km
Pacific Ocean
Atlantic Ocean
Indian Ocean
Asia
Africa
EuropeNorth America
South America
Sea route
N
Arctic Ocean
Australasia
°
Why are oceans important?Why are oceans important?Unit 4 The importance of oceans
Fish for food
Oceans are rich in animal life. There are 20 000 species of fish in the oceans.
Why are oceans important?Why are oceans important?Fish for foodFish is a major sour
ce of food, today fish supplies almost 20% of the world’s animal protein.
Unit 4 The importance of oceans
Why are oceans important?Why are oceans important?Fish for foodFish caught are used for the
making of animal feed, fertilizer, soaps and other commercial products.
Millions of people depend upon fishing for their livelihood.
Unit 4 The importance of oceans
Why are oceans important?Why are oceans important?MineralsOceans are rich in minerals.Tin, gold, platinum and
diamonds are found in the sand and gravel along the shore.
Unit 4 The importance of oceans
Why are oceans important?Why are oceans important?MineralsSea water is an important source of salt and
fresh water.
Unit 4 The importance of oceans
Why are oceans important?Why are oceans important?Continental shelves are gently sloping plains beneath the sea bordering the continentals. They are no more than 100 fathoms (180m) deep.
Energy
Unit 4 The importance of oceans
Sea level
100 Fathoms
Continental shelf
Land
Why are oceans important?Why are oceans important?
Energy
Oceans are a potential source of renewable energy.
Modern technology has made the mining of oil in the deep sea possible.
It is possible to make use of sea waves and tidal currents for the generation of electricity.
Unit 4 The importance of oceans
Why are oceans important?Why are oceans important?Ocean-atmosphere system
Oceans act as a store house for the heat energy coming from the sun.
The stored heat is then radiated back to the atmosphere thus keeping the atmosphere warm.
Unit 4 The importance of oceans
The ocean-atmosphere systemThe ocean-atmosphere systemUnit 4 The importance of oceans
Sun
Less solar energy
Ocean
More solar energy
Warmer water
Equator
Colder water Colder water
Arctic circle Antarctic circle
0°66 1/2°N 66 1/2°S
Surface
Cold current
Warm current
Ocean absorbs sun’s energyOcean warms the atmosphere and supplies it with moistureWarmer water flows to colder sea forming warm ocean current Colder water flows to warmer sea forming cold ocean current
Atmosphere
Ocean-atmosphere system
Our oceans supply the atmosphere with moisture and heat.
The heat absorbed by the ocean is released to the atmosphere when air comes into contact with the ocean surface.
The air also absorbs from the ocean its moisture.
When this wet air blows onshore from ocean to land, it brings rain to coastal areas.
Why are oceans important?Why are oceans important?Unit 4 The importance of oceans
Why are oceans important?Why are oceans important?Ocean currents and climate
Difference in temperature leads to the different density of water over various parts of the ocean. The result is warmer water moves from tropical areas to polar areas while colder water moves from polar areas to tropical areas.
Ocean currents influence the temperature of the coastal regions they flow past. A warm current raises the temperature of the coast while a cold current lowers it.
The effect of the movement of ocean currents is important to our climate as it reduces the extremes in temperature of both the oceans and the atmosphere.
Unit 4 The importance of oceans
Ocean currents of the worldOcean currents of the world
Arctic Ocean
Pacific Ocean
Indian Ocean
Atlantic Ocean
Cold current Warm current
Bra
zil c
urre
nt
West Wind Drift
Peruvian Current
California C
urrent
North A
tlantic
Drif
t
Europe
Can
arie
s C
urre
nt
Asia
Benguela Current
Africa
West Australian Current
km
Australasia
North Equatorial Current
East Australian Current
South Equatorial Current
Kuro SiwoOya
Siw
o
Agu
lhas
Cur
rent
Labrador
Current
Gulf Stre
am
North America
South America
°N
°N
°S
N
Unit 4 The importance of oceans
Rain
Clouds
Ocean
Condensation to form clouds and rain
Wind moves up the slope and cools
Wet on-shore wind
On-shore wind from ocean brings rainOn-shore wind from ocean brings rainThe air absorbs from the ocean its moisture. When this wet air blows on-shore from ocean to land, it brings rain to coastal areas.
Unit 4 The importance of oceans
Hong Kong
Fog
Pacific Ocean
Cool sea surface
Warm tropical air moves northwards
South China Sea
N
Why are oceans important?Why are oceans important?Fog and typhoonsIn Hong Kong fog occurs in spring when warm
air passes over the cold sea surface.
Unit 4 The importance of oceans
Why are oceans important?Why are oceans important?Fog and typhoonsWe receive a lot of rain in summer as winds blow
in from the ocean.
Condensation forms fog
Warm tropical air move northwards
South China Sea
Sea surface still cool in spring
Unit 4 The importance of oceans
Hong Kong Pacific Ocean
Tropical sea supplies typhoons with heat and moisture
Routes of typhoons
N
Why are oceans important?Why are oceans important?Fog and typhoons Typhoons affecting us in the summer season
obtain their moisture and heat from the ocean. The heat produces an enormous amount of energy
which makes these storms very destructive.
Unit 4 The importance of oceans
Terms to learn
Continental shelf (Continental shelf ( 大陸架大陸架 )) -- a gently sloping plain beneath the sea bordering a continent. It is no more than 100 fathoms (180m) deep.
Renewable energy (Renewable energy ( 再生能源再生能源 )) -- energy that will never be used up. Sea waves and tidal currents are examples.
Unit 4 The importance of oceans