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Alaska
In 1867 the USA bought Alaska from the Tsarist government of Russia for a mere $7 million. More extensive then the south-western lands acquired from Mexico, Alaska remained a territory for over 90 years, becoming America's largest state in 1959. Geographically it forms the north-western end of the Western Cordilleras; peaks in the main Alaska Range rise to over 6000m (20,000 ft), and the southern 'panhandle' region is a drowned fjordland backed by ice-capped mountain. A gold rush in the 1880s stimulated the later development of other mineral resources - notably copper and, especially, oil. Alaska is the first real test of the USA's resolve to balance economic development and conservation; the six largest US national parks are in Alaska. Some farming is possible on the southern coastal low-lands; the interior is tundra-covered and rich in migrant birds and mammals.
The Amazon
Though not the world's longest river - 6430 km (3,990mi) - the Amazon is easily the mightiest, discharging some 180,000 cu m/sec (6,350,000 cu ft/sec) into the Atlantic, more than four times the volume of its nearest rival, the Zaire. The flow is so great that silt discolors the water up to 200 km (125 mi) out to sea, and the river accounts for a fifth of the world's total discharge into the oceans.
The Amazon starts its journey in the Andes of Peru - only 150 km (95 mi) from the Pacific - at Lake Villafro. Navigable to ocean-going vessels of 6000 tons up to the Peruvian jungle port of Iquitos, some 3700 km (2,300 mi) from the sea, it joins the Negro at Manaus, where the river levels can vary by over 15 m (50 ft) in a year.
Along with more than 1000 significant tributaries, seven of which are more than 1600 km (1,000 mi) long, the Amazon river drains the largest river basin in the world - about 7 million sq km (2.7 million sq mi) - nearly two-fifths of South America and an area more than twice the size of India. This vast system provides a crucial network of communications.
Antarctica
Antarctica is a vast continent of rock covered with ice and surrounded by oceans. It is totally different from the Arctic which is an expanse of frozen ocean surrounded by continents. Antarctica is twice the size of Australia.
Ice is the major feature of Antarctica. It covers 98% of the continent and is partly responsible, along with Antarctica's position at the pole, for the extremes of wind and cold.
Only about 2% of Antarctica is ice free. One of these areas is called Dry Valleys in the Ross Dependency. It is the driest place on earth - no rain has fallen for at least two million years! In one of the Dry Valleys however, there are lakes filled by rivers that flow inland during the brief summer.
Over most of the continent though, the ice cap is so thick that it has pushed down the underlying rock. The ice cap covers 13.72 million square kilometers and contains 90% of the world's ice and 70% of the world's fresh water. The highest elevation of the ice cap is 4100 m and, in places, covers entire mountain ranges. The ice flows downhill from the highest points in the ice cap towards the coast.
Arctic Ice
The two arctic regions of the world (at the North and the South Pole) are mostly covered in a thick ice cap. This ice cap has an average thickness of about 1.5 km.
The waters around the arctic regions have a temperature of -1.5º C. This means that these waters are constantly frozen.
When humans want to reach the North or the South Pole, they have to go on foot, especially the part of the ice which is the closest to the center of the poles; the first part they can use an icebreaker.
An icebreaker is a boat of which the bow is made stronger so that it can break through the thick ice cap of the arctic regions of the world. These boats are used mostly by scientists who are studying these regions. Sometimes these boats are used to free ports from ice. Ports which are frozen in the winter need to be freed of the ice in order to make them accessible for boats. Ports which are frozen in the winter are, for example, St. Petersburg, Russia; Helsinki, Finland; Halifax, Canada.
Arctic Ocean
The Arctic Ocean is in the North Polar region and is the smallest of the oceans. It is nearly landlocked being surrounded by Russia, Alaska, Greenland, and Norway. About 70% of the Arctic Ocean is covered by the polar ice cap for the entire year. Some of the ice cap melts in the summer but refreezes in the winter. The temperature of the surface waters range between -1.4° C in the summer to -1.7° C in the winter. The salinity varies between 28 and 32 °/oo. Water enters the Arctic Ocean through the Bering Strait in the Pacific and the Norwegian Sea in the Atlantic. Twice as much water enters from the Atlantic side as the Pacific. Other ways in which the Arctic receives water is from precipitation and runoff 'fro land'. Most of the water leaves the Arctic Ocean by the Greenland Current. Some parts of the Arctic Ocean are 4000m deep.
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Arctic Ice |
The climate in the Arctic
The climate in the Arctic is very rough and unpredictable. One thing is for sure: it is always very cold. But a storm can come up in a few minutes. When humans go to the Arctic they have to be prepared for the worst, they have to be dressed in several layers of clothing and they also have to watch out for animals, such as polar bears.
Because the arctic regions of the world are around the two poles, the day times are very different then we know them. In the winter it is always dark; the sun does not come up. In the summer it is always light; the sun does not go under. This is caused by the rotation and tilt of the earth.
Cetaceans
All dolphins, porpoises, and whales belong to the order Cetacea. They are often called Cetaceans. The cetacea evolved back to the sea from land, and their bodies have undergone many changes in their form or anatomy and their physiology to cope with a life spent entirely in the water. They breath through blowholes, which have migrated to the top of their heads to make breathing easier when swimming. The blowhole is an external nostril. They are powerful valves which are tightly closed during submersion. The length of time under water varies with species. A sperm whale can hold its breath for 1 hour, dolphins 7-15 minutes. They breathe 1 to 4 times per minute. Their forward appendages have become flippers and their hind ones have nearly disappeared. They have small traces of bone embedded deeply in the muscles. Both whales and dolphins have lost their hair and external ears.
Scientists group most dolphins (31species) in the family Delphinidae, part of the suborder Odentoceti, or toothed whales. Delphinids include such well known dolphins as bottle nose dolphins and common dolphins as well as the family Delphinidae.
A dolphin has streamlined body parts that help it swim through the water. The "dorsal fin", located on the center of its back, is made of dense fibrous connective tissue - there is no bone inside. The dorsal fin acts as a keel, giving the dolphin some stability as it swims.
A dolphin breathes through a single "blowhole", located on top of its head. A muscular flap covers the blowhole, making a watertight seal when dolphins dive. To take a breath, dolphins contract the muscular flap. When dolphins relax the muscles, the flap stays tightly closed. They breath 1 to 4 times per minute.
Dolphins live in all oceans of the world. While some inhabit one particular geographical area of an ocean, others like killer whales are found worldwide. Coastal, or inshore, dolphins live close to land and are often seen by people on beaches and boats. Many dolphins have a home range, an area where they tend to stay.
Dolphins live and travel in groups called "pods", often family groups. In some species, individual dolphins enter and leave the pod over time. But others, like killer whales, have a stable group. Sometimes, several pods may join together to form a temporary herd. Several hundred individuals have been seen traveling in a single herd.
These social mammals communicate by squeaking, grunting, trilling, and moaning. They also send messages through body language by leaping, breaching, smacking their tails against the water, butting heads, and jaw-snapping. Within the pod, some dolphins are more dominant than others.
HUMAN ACTIVITIES CAN HARM DOLPHINS!
In some parts of the world, humans hurt certain types of dolphins for food. Yet even where they are not hunted, dolphins are threatened by some human activities.
Toxic chemicals that pollute near shore waters may contaminate the fish on which dolphins feed. Scientists believe these chemicals might affect the health of dolphins and cause tumors. Pollution may have contributed to the death of dolphins that have washed up on beaches in recent years.
In the eastern tropical Pacific ocean, tuna travel under dolphin pods. When tuna fishermen set their nets around the dolphins to catch the tuna, the dolphins are trapped too. To help save dolphins, many tuna fishermen now use special nets and techniques to release the dolphins. From 1972 to 1994, dolphin deaths from purse seine fishing in the eastern tropical Pacific dropped more than 99%, from 423,678 to 4,095 individuals.
WHAT YOU CAN DO FOR DOLPHINS
- Reduce, reuse, and recycle your trash so it doesn't end up in the ocean.
- Encourage friends and family to properly dispose of toxic waste like paint and car oil at special collection sites, rather than pouring them down the drain.
- Support aquariums, zoos and museums that conduct accredited dolphin conservation programs.
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The Old Porpoise
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| An eddy is a whirlpool that can be many miles wide. The eddy in the story formed from the Gulf Stream. Sometimes it meanders like a river and makes a loop in the current. When the loop pinches off by flowing back on itself, it becomes a large eddy. The eddy then moves through the ocean much like a storm moves through the air. The edges of the Gulf Stream are called oceanic fronts. Eddies can be made on either front of the main current. To the north (3a) or to the south (3b) as shown on the diagrams.
When the Gulf Stream loops to the north to make an eddy, Sargasso Sea water is trapped in the center. Because Sargasso Sea water is warmer than the water in the eddy, it is called a "warm core" eddy (4a). The water in these eddies move in a clockwise direction. When the Gulf Stream loops to the south, the eddy that is formed traps cold water from north of the Gulf Stream. The cold water is called "Slope water", because it occurs over the continental slope. These eddies are "cold core" eddies (4b). The water in these eddies move in a counterclockwise direction.
The warm core eddies (on the north front of the Gulf Stream) either disappear when they mix with the surrounding cold water, or they drift to the southwest and rejoin the Gulf Stream. The cold core eddies (on the south front of the Gulf Stream) move to the south and eventually disappear when they mix with the surrounding Sargasso Sea water.
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The concept of energy is introduced in the story in association with the eddy in the Gulf Stream. For a movement to continue, it must have a source of energy. The example used in the story is the energy from the Gulf Stream that has transferred to the eddy. The eddy could only continue moving for a period of time that it took to use up its given energy. Without that energy to maintain it, it had to dissolve.
English Channel
The English Channel is the body of water that occurs between England and France. It is very narrow, and when the weather is very clear you can see across it. The climate is temperate, and most of he time, it's windy, cloudy, and rainy. The oceanography is variable, and the tides are very strong. Waters flow from the North Atlantic through the Channel to the North Sea. This small sea is the busiest of the world, every day a lot of boats sail the English Channel on their way to Rotterdam (the largest seaport in the world), Brest, Hamburg, and others.
A front or a boundary is the change that occurs between bodies of water with different temperatures and/or salinity. It also happens when two currents move against each other because they move in different directions or at different speeds. Or if they move in the same direction, one current is moving faster than the other. It is possible that on one side of the front it is very sunny and calm, and on the other side it is very cloudy and windy.
Recognized by geographers as the world's largest island (the Australian mainland being considered a continental land mass), Greenland is almost three times the size of the second largest, New Guinea. However, more then 85% of the land is covered in continuous permafrost, an ice-cap with an average depth of about 1500m (5,000 ft), and though there are a few sandy and clay plains in the ice-free areas, settlement is confined to the narrow rocky coasts. The few ones, including the capital of Godthåd (Nuuk), are on the south-west coast, warmed by northward currents of the Atlantic; on the east side, a southward current from the Arctic chills the pack-ice and makes it inaccessible for most of the year.
The economy still depends substantially on subsidies from Denmark, which remains its chief trading partner. The main rural occupations are sheep rearing and fishing - with shrimps, prawns and mollusc contributing over 60% of exports. The only major manufacturing is fish canning, and most Greenlanders (a mixture of Inuit Eskimo and Danish extraction) live between the primitive and the modern.
The Gulf of Mexico is situated on the eastern side of Mexico and on the southern side of the United States. It is considered a small ocean basin with a wide, shallow shelf along the United States coast and the Yucatan Peninsula and exists to the North Atlantic through the Florida Straits. A prominent feature in the Gulf of Mexico is the Loop Current. It is formed by the Yucatan current, extends into the central eastern Gulf and flows out through the Florida Straits as the Florida Current. Along the coast of the United States, there are many freshwater rivers that enter the Gulf. The Mississippi is the largest, and during periods of high flow, it's influence can extend to 150 km offshore. A lot of oil is found in the Gulf by countries as the United States and Mexico.
Herring
Herring are little fish which move in large schools. They belong to the phylum Chordata, class Piscis. They are further divided into the family Clupeids, which are pelagic fish typical of upwelling areas. They make up about 27% by weight of the world catch of fish. Although some of the catch is eaten fresh, canned and pickled, most is ground into fish meal, a protein additive used in agriculture for poultry and pigs. The herring fishery comes and goes. There have been fishing periods that were exceptionally good, lasting between 60 and 70 years. Then a lapse of 30 to 40 years would occur when there would be little or no herring. At one time no one knew from where the herring migrated. They always arrived in great quantity and at unpredictable intervals.
There is a northern group called the Atlanto-Scandinavian because they are north of the North Sea. They seem to be widely distributed in the North Atlantic and migrate seasonally to spawn. These fish are slow growing, reach maturity in 5-8 years and live up to 20 years.
A southern group of herring is caught in the North Sea. This fish has been economically the most important and the most abundant species caught in the Northeast Atlantic. These fish mature in 3-4 years and live up to 11 years. They winter on the east side of the North Sea in the Norwegian channel. They migrate to the British Coast in summer to feed and spawn.
The North Sea herring deposit their eggs in thick blankets to cover 100 sq. meters of the continental shelf. The eggs are a favorite food for Haddock.
After a few weeks, the larvae look like tiny eels, about 5 mm (2.5in). The larvae break free of the egg membrane and swim to the surface. These then are eaten by some zooplankton called ctenophores and arroworms. When they become 15mm (1.5in) long, they grow scales and look like fish. They begin to school and travel toward the shallow water and enter the bays to eat and grow. In 6 months they disperse in the North Sea and when sexually mature they join schools of spawning fish and repeat the cycle.
The Dutch were the first to have developed an open sea herring fishery. By the 15th century, drift nets were used, and the catch was cured with salt in barrels and then traded extensively, particularly in the hinterland of in the Southern Baltic.
By the 18th century Sweden and then Norway became the predominant fishery. In the 19th century, the Scots developed the fishery. They were easy to catch as they breed off their coast, and after the fish spawns they are less active and lie on the bottom.
Increasing echo sounding to locate and better trawls has all but depleted this fishery.
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One of Victor's many friends |
Ice formation and Icebergs (Ice Floes)
Ice forms in fresh water when the temperature of the water drops beneath O° C. Because the oceans are salty, sea ice in the Polar regions forms when the temperature drops to about -1.8° C.
On the North and South Poles, the temperature never reaches above O° Celsius, therefore that part of the earth is always covered in ice. There are two types of ice found in the Arctic. One is sea ice formed on the ocean, and the other is glacial formed on land and eventually flowing into the ocean and becoming icebergs. Ice bergs and sea ice float on the surface of the water because ice becomes less dense or lighter than the surrounding water, much like an ice cube floats in a glass of water.
The life cycle of a typical iceberg found in the North Atlantic today might look something like this:
| TIME LINE
1000 B.C.
950 B.C.
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1993 A.D.
1996 A.D.
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ICEBERG DEVELOPMENT
Snow/Firn
Ice/Glacier
Glacier movement
Calving
Iceberg melt
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Snow falls on the ice cap of Greenland. Over the course of several months it changes into firn, which is basically a granular snow. Several decades later it is compressed into very dense ice by the weight of the firn and snow that have accumulated on top of it. Driven by the enormous weight of the ice cap above, the ice begins to flow seaward through openings in the fringe of the mountains (thinking of it like water leaking out of a cracked bowl may help). This force moves the rivers of ice known as "glaciers" up to 18 m (60ft) a day, eventually pushing the ice to Greenland's western coast.
At the glacier's terminus or end, huge slabs of ice are weakened and then broken by the action of the rising and falling tides. This process is called "calving" and results in an iceberg's birth. By the time these mountains of ice enter Baffin Bay they have seen nearly 3,000 years pass. Once waterborne, icebergs are driven by strong subsurface currents, the cores of which are located at a depth of approximately 50m (this occurs because 7/8 of an icebergs mass rests below the waterline). Therefore, deeper currents have a greater surface area to push against, compared to winds or windmade surface currents. This is why it is not uncommon to see icebergs heading directly into strong winds. In order for an iceberg to reach the North Atlantic the currents typically take it from Baffin Bay through the Davis Strait and Labrador Sea. This is a long trip and most icebergs never make it. Most icebergs melt well before entering the Atlantic Ocean. One estimate is that of the 15,000 to 30,000 icebergs produced annually by glaciers of Greenland only one percent (150 to 300) ever make it to the Atlantic Ocean. When an iceberg does happen to reach the Atlantic, its long and traveled life quickly comes to an end melting rapidly in the warm waters. At the most it will take two months to melt, unlike icebergs stuck in parts of Baffin Bay where it can take up to 4 years for a berg to melt.
Iceland
Situated far out in the North Atlantic Ocean, Iceland is not only the smallest but also the most isolated of the independent Scandinavian countries. Though politically part of Europe, the island (nearer to Greenland than to Scotland) arises geologically from the boundary between Europe and America - the Mid-Atlantic Ridge. It is indeed a product of the ridge, formed almost entirely by volcanic outsporings at a point where the Earth's crust is opening at a rate measurable in centimeters per year.
Iceland boasts the lowest infant mortality rate in the world and the highest life expectancy outside Japan.
Jellyfish
A jellyfish is an Invertebrate (boneless) animal. They belong to the phylum (race) Coelenterata and class Hydozoa and Cubozoa. It has a disc or bell-shaped body usually with long tentacles. It is free swimming, but generally floats with the currents.
Jellyfish range from a mere 12mm to more than 2m across. The largest is Cyanea artica, which may have tentacles over 40m long! Despite their often enormous size, jellyfish have no head, no skeleton, and no special organs for respiration or excretion. Their life cycle involves an alternation between sesslie polyp phase and a free-swimming medusa stage, though the medusa stage usually predominates.
True jellyfish are graceful, and sometimes deadly creatures. Their stings may cause skin rashes, muscle cramps, or even death.
Jellyfish are not terribly important as a food source, though they are eaten in some countries. In northern waters, large schools several kilometers long sometimes hamper fishing by clogging nets.
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Jill the Jelly |
A kelp forest is made from seaweed and a plant called Kelp. Kelp, a brown algae, is a water plant which grows on a rocky ocean floor in water with a temperature of 5° to 22° C. The kelp forest is found along open coast lines. The giant kelp, Macgocystis pyrifera, is the most famous one. It is found in cold waters around the world. Other well known kelps are the Ecklonia radiata on the Southern Hemisphere and the Laminaria-species, which are found on the Northern Hemisphere.
The kelp forest is the habitat of many animals, such as sea otters, sea stars, crabs, and little fish.
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Forrest |
This is a room where scientists do scientific research. They study all sorts of different phenomena and ideas, like how the ocean currents flow through the oceans, how animals live and behave or the chemistry of the oceans.
Laboratories are also used by medical researchers to make medicines and look for cures for diseases.
Life cycle in the Ocean
"Primary production" of organic matter by plants from sunlight and nutrients through the process of photosynthesis. It forms the first link in the food chains that link plants, Herbivorous animals (animals who only eat plants), and Carnivorous animals (animals who only eat meat). Together they make up the total production of the sea. Where there is high primary production there are large populations of animals.
Animals are consumers, they feed on the primary producers or on other consumers. Herbivores and carnivores are still ultimately dependent on the primary producers for their food. The most numerous and greatest bio mass of herbivores are the plant-eating zooplankton. These animals are the primary consumers which convert plant tissue to animal tissue. In turn, they become the food for the other zooplankton, the carnivores or secondary consumers.
There may be many or few links in the food chain that lead to the top carnivore, a predator on which no other organism preys. Food chains are rarely simple, there more often very complex relationships among the organisms. These interconnecting food chains are called food webs.
Idealized Food Chain
primary producers ==> primary consumers ==> secondary consumers ==> top carnivore
Longitudes and latitudes
Longitudes are the vertical or "meridional"lines which run from the top of the world (the North Pole) to the bottom of the world (the South Pole). The lines meet at each Pole and are used to show distance East or West of the Prime Meridian. The Prime Meridian is 0° longititude line and passes through Greewich, England. Latitudes are the horizontal or parallel lines that circle the Earth's surface to show distance Northward or Southward from the equator. he equator is the 0° latitude line. Sailors use these lines to navigate their boats around the world and give their position for latitude as the number of degrees north or south of the Equator and the number of degrees east or west of the Prime Meridian.
In the early days of exploration, navigators had to use elements of the earth and sky to determine where they might be. The early navigators noticed that the position of the sun followed the same path everyday, and the arrangements of the stars appeared to be in the same locations at night. If the navigators traveled to other locations north or south, they saw that the stars would appear at a different location in the sky or disappear. From these observations, they learned to judge direction. The Portuguese developed a method to measure the angular relationship between the stars and the horizon. What they were measuring was the latitude. In the Northern hemisphere, the North Star, Polaris, was used for reference, and in the Southern hemisphere, the Southern Cross was used.
Long Key is a part of the Florida Keys. These are a group of islands attached to each other by a very long highway, which includes many bridges, one of which is the Seven-Mile-bridge and is the longest. These islands lay to the south of Florida. The largest one is Key West; this is also the last island which can be reached by car.
Marine Mammals
Marine Mammals belong to the phylum or race of the Chordata and class of the Mammalia. There are 111 species of marine mammals. They are warm blooded, nurse their young with milk, and gain their living from the sea. They vary in shape from the small sea otter to the great blue whale. They are rich in oil and protein, and are covered with valuable fur. When they are born, they are wide-eyed and able to swim. They wear fur jackets or blubber. A whale's blubber is about 6m thick, and it peels like an orange. A fur seal has 762,000 hairs/sq. cm (300,000 hairs/sq. in) with oily underfur. This traps millions of tiny air bubbles to provide thermal insulation. The blubber of a walrus is around 1/3 of its body weight and a right seal is about 1/2 of its body weight. This is to protect them from the cold. They are exposed to winds and temperature as low as -30° C (-40° F). Their blood systems have arteries to carry warm blood to their flippers, tails, and extremities. The arteries are closely surrounded by veins which carry colder blood back to the deep body.
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Furry Animal |
North Africa stretches from Egypt in the east to Morocco and Western Sahara in the west. In the north the Mediterranean coast has a sunny climate and therefore tourism is very important, the south is covered in sand and is called the Sahara Desert. The largest country in this area is Algeria.
The area north of the Sahara includes the sharply folded and eroded Atlas Mountains; the coastal and Nile valley lands were the home of the ancient civilization of Egypt, with evidence of early Phoenician, Greek, Roman and Muslim contacts. The Sahara Desert stretches across Africa from west to east, containing the mountain massifs of Hoggar and Tibesti; lowlands to the east are threaded from south to north by the Nile Valley.
North Atlantic Ocean
The North Atlantic Ocean is a very cold and rough place. The further you go north the colder it gets and a large piece of the North Atlantic Ocean is covered in ice throughout the year. Even though this place is very cold, a lot of animals live there.
North Pole
The North pole sits on the top of the world and it is very cold up there. This part of the world is always covered in a thick layer of ice. Some part of the North pole are covered in a small layer of ice. Some boats, called Icebreakers, can travel through this layer of ice.
The North Sea occupies the shelf area between the British Isles and Norway, Denmark, Germany, Holland and Belgium. The waters in the North Sea come from the Atlantic through the English Channel and from the north between Scotland and the Faeroe Islands. The North Sea also receives waters from the Baltic.
Some parts near the southeastern coastal areas are icecovered in the winter. The most extensive ice cover is in February. In severe winter, ice lasts for 60 days and up to 90 or 130 days at several places. In April the area becomes ice free. Ice in the western part of the North Sea rarely forms due to the North Atlantic warm salty water.
One of the world's most distinctly shaped countries, the Kingdom of Norway occupies the western part of the Scandinavian peninsula. Norway has a population of less than 4.3 million, most of whom live in the southern part of the country, where the capital, Oslo, is situated. Nowhere in Norway is far from the sea. At the widest point it is only 430km (270mi) from west to east, and near the Arctic port of Narvik the Swedish border comes to within 6.5km (4mi) of the Norwegian coast. A third of Norway lies within the Arctic Circle, but the climate is not as severe as might be expected because the Norwegian coast benefits from the moderating effects of the warm waters of the North Atlantic Drift. Even on the Arctic coast, the ports of Hammerfest and Kirkenes remain unfrozen in most winters.
The sea has always been a major influence in Norwegian life. A thousand years ago Viking sailors from Norway roamed the northern seas, founding colonies around the coast of Britain, Iceland and even North America. Today fishing, shipbuilding and the management of merchant shipping lines are of vital importance to the Norwegian economy, and its merchant ships, most of which seldom visit home ports, earn profits which pay for a third of the country's earnings.
Norwegian Sea
This sea is a part of the North Atlantic Ocean and it has the same characteristics. On its east is the coast of Norway and extends up to North Cape to Bear Island on to the southern end West Spitsbergen. The west side extends from Jan Mayan Island past Iceland down to the Faroe Islands to the south.
The air over the Norwegian Sea is called Polar Maritime. The air temperature ranges from -9° Centigrade in winter to 11° C in summer. The water temperature near 100 m ranges between 9° C in the southern part to 6 degrees C near Spitsbergen. While the upper water is the same as the North Atlantic, a Norwegian Deep water is formed in winter near Jan Mayen Island. This water is a mixture of Atlantic and Arctic water, and when it cools to -1° C it sinks to about 1,000 m. Deep water below this is nearly the same temperature, -1° C, and salinity, 34.9 psu.
There is a ridge that runs along the bottom between Faroe Islands and Iceland called the Faroe-Iceland Ridge This ridge separates the bottom waters of the Norwegian Sea and the Atlantic Ocean. Sometimes bottom water will flow southward over the ridge into the Atlantic.
About 3 to 6 million cu m/s of water from the North Atlantic enters the Norwegian Sea south of Scotland. It becomes the Norwegian Current which flows northward along the coast of Norway to the Barents Sea. The current splits and some flows into the Barents Sea, and some flows west towards Spitsbergen. Some water enters from the North Sea, and some from by runoff from the Norwegian coast.
Nutrients are important chemicals in the ocean. They are eaten by the phytoplankton, large seaweeds, sea grasses and some animals. Nutrients along with sunlight are used by the plants to grow. These are the same nutrients that a farmer uses on his land to make his crops grow. The most important nutrients are nitrogen, phosphorus, silica, and iron. The areas of the oceans that have the most nutrients are near the coasts. This comes from the many rivers that flow into the sea. The rivers carry the nutrients from the land and deposit them into the ocean. Upwelling areas also have high nutrients. When the deep ocean rises to the surface, it brings nutrients for the plants to use and grow.
Today, "Oceanographer" is a term that is usually understood to include ocean scientists, ocean engineers and ocean technicians.
Ocean scientists investigate how the oceans work. They usually have a graduate education in oceanography, but have studied one of the fundamental science fields at the undergraduate level, such as physics, chemistry, biology or geology. Ocean scientists take measurements on samples at sea, obtain "remote sensing" data from artificial earth satellites, perform laboratory measurements on samples, and conduct models on computers. The recognized subfields of oceanography are physical oceanography, chemical oceanography, biological oceanography, and geological and geophysical oceanography.
Ocean engineers function in several important roles in oceanography. First, they pursue their usual tasks, such as designing a structure, but the environment in which their design is to function is the sea. For example, the designer of a tower to stand on the sea floor on the offshore continental shelf and support oil well drilling equipment would apply many of the same design procedures that would be used to design such a tower to stand on the nearby land. However, the engineer designing the ocean-standing structure would be required to incorporate into the design additional information about ocean currents and resulting structural forces, salt water corrosion, marine life fouling, and other similar factors. A second role of ocean engineers is the design of equipment and procedures to be used in making oceanographic measurements. This work is usually carried out best in cooperation with ocean scientists. The ocean engineer today plays an important role incorporating the new concepts from the forefront of the present explosion of technology into oceanographic instrumentation. This is especially true in experimental studies of hydrodynamics and of the sea floor sediment dynamics.
Ocean technicians play a vital role in oceanography. They are responsible for equipment calibration and preparation, measurements and sampling at sea, instrument maintenance and repair, and data processing. These technicians normally have a bachelor's degree, although some have associate's degrees resulting from two-year college programs.
Oceanographers are often specialized in one area of expertise. This can be in oceanography in the Arctic regions of the earth, or oceanography in only tropical waters. This means that they only do research in these waters and nowhere else.
Currents in the oceans are formed by heating from the sun, rotation of the Earth, and the winds blowing on the water. There are surface currents and deep currents. The winds and rotation of the earth are the primary force of the large surface currents. They cause the water to move like a stream flowing along a path.
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Surface currents move in a circular path along the coasts of the continents in a clockwise direction in the northern hemisphere and counterclockwise in the southern hemisphere. Because the winds blow continuously across the oceans, surface currents are always present. All the important currents in the world have been named.
The Gulf Stream (see illustration) is the most famous ocean current, and we know a lot about it. Of all the ocean currents, it is the fastest and most powerful one. Its speed is about 8kph (5mph), which is very fast for a current. Most currents are very slow and travel less than 0.16 kph (1mph). Gulf Stream water that began near Miami, Florida takes 9 months to cross the Atlantic Ocean to reach Ireland and one full year to reach Norway. Off the coast of Florida, the Gulf Stream moves 6 billion gallons of water each second. A similar current that flows off the coast of Japan is called the Kuroshio. Kuro means warm, and shio in Japanese means current, so Kuroshio means 'warm current'.
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Warm currents move from the equator towards the North and South Poles and carry heat to the Poles. If a warm current flows close to a continent, it will help to keep the land near the coast warm. For example, the Gulf Stream is a warm current and it helps to keep the east coast of the United States warm. The waters around Norway do not freeze because of the heat carried by the Gulf Stream to that part of the North Atlantic. Greenland is opposite Norway, and the waters around this country do freeze. This is because cold water moves from the Arctic Ocean southward along the coast of Greenland. In fact, cold currents come from the poles and carry cold water to the equator. The cold water from the poles is heavier than the warm water from the equator and will sink under the warm water south of Iceland. The cold water becomes a deep flowing current. These currents flowing opposite each other maintain a balance in the oceans so that they do not get too hot or too cold.
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World Currents
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Periscope ('Eye of the Iron Fish')
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The word 'periscope' literally means to look ('scope') around ('peri'). It is a pipe with mirrors used in submarines. The person inside is able to see what's going on above the surface of the water. |
Phytoplankton
The phytoplankton belong to the classes of the Bicillariophycae (Diatoms), the Chlorophtya (green algae), and the Cyanophtya (blue-green algae). Phytoplankton are microscopic plants that float with the currents and live in the sunlit areas of the ocean down to about 50 meters. This is called the photic zone. Phytoplankton use nutrients to grow, have chlorophyll, and they photosynthesize like the land plants do. Photosynthesis means that they make food from carbon dioxide and water by using the energy from the sun and releasing oxygen. This process is called primary production, and the phytoplankton are called primary producers. The coastal waters and upwelling areas have the highest primary production.
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Little plants |
Russia
It is an indication of the sheer size of the former Soviet Union that, having shed very nearly a quarter of its area with the departure of the 14 republics in 1991, its Russian Federation remains the largest country in the world, still almost twice the size of Canada, China or the USA. This territorial immensity brings a number of disadvantages - it is awkward to administer; large investments have to be made in the transport system, and the long borders are difficult to defend - but set against these are the benefits that derive from the diversity of environments and cultures and the abundance of resources in the country's vast expanses, many of which are relatively untouched.
Russia has been a centralized state throughout its history. A major landmark in the country's history, and indeed in the history of the world, was the 1917 Revolution, when the Tsarist order was overthrown and a Communist government established under Lenin - replacing one form of totalitarianism with another. The years from 1917 witnessed colossal changes in the political, social and economic structure of the country, the most dramatic and far-reaching of which took place from the 1930s when Stalin instituted central planning of the economy, collectivized agriculture and began a period of rapid industrialization. After Stalin's death in 1953, Soviet leaders modified some policies but remained true to the general principles of Communism until the radical approach of Mikhail Gorbachev changed the face of Russia - and in the process most of the Communist world. This meant the beginning of the end for the Communist world. In 1989 the Berlin Wall fell and in 1991 the Soviet Union fell apart.
The class of Gastropoda is the largest class of the mollucs. Many of the 80,000 species have evolved for life in different habitats and can be found in the open ocean, in fresh water and on land. Most species used as food, however, inhabit shallow coastal areas, particularly rocky or coral reefs.
Although only a few Gastropods, particularly Abalone, are the bases of valuable seafood export industries, many other species with a large and fleshy foot are collected as food in coastal areas. Additionally, many Gastropod species are valued in the ornamental shell trade and for sale to tourists, because of the diversity in form and color of their shells.
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Carrie the Conch |
Sea turtles
Sea Turtles belong to the phylum or race of the Chordata (backbones or vertebras) and the class Reptilia. They are graceful saltwater reptiles, well adapted to their marine world. With streamlined bodies and flipper-like limbs, they are able to swim long distances in a relatively short time. Sea Turtles have a hard horny shield or carapace. They have a three-chambered heart whose blood stays near the same temperature as that of its surrounding environment. Turtles are cold-blooded and thus cannot stand very cold sea water. This limits their range to warm ocean waters. Turtles have five-toed feet and claws. Their front legs are paddle shaped with very long fingers. Their front feet are for swimming, while their back feet act like steering oars. They move along at about 6 kph (4 mph).
Turtles range in size from 45cm to 180cm (18 - 70in) and weigh 90kg to 180kg (200 - 400 lbs) or more. The teeth are in the front half of the lower jaw. The upper jaw is like a beak. It is a horny plate for shearing. They use their front legs and beak for protection. The front legs act as clubs or swords, and the beak can shear a 5 by 10cm (2 by 4in) piece of wood with a slash!
When they are active, they must swim to the ocean surface to breathe every few minutes. Generally, they breathe about every 2 minutes and can stay underwater for 12 to 25 minutes. When they are fully resting, they can remain underwater for as long as two hours without breathing.
Although sea turtles live most of their lives in the ocean, adult females must return to land in order to lay their eggs. Scientists believe that nesting female turtles return to the same beach where they were born. Just how sea turtles find their nesting beaches is unknown. Often sea turtles must travel long distances from their feeding grounds to their nesting beaches. Once every two or three years female sea turtles make the journey from their feeding area to the beach where they will lay their eggs. The females lay their eggs in the sand. She covers them up to disguise them and makes a decoy nest. The mother then returns to the sea to a waiting male. She mates again after laying her eggs. The male patiently waits in the water for her return. She swims around to pick out a mate. She rejects a male by swimming with her body upright and a facial motion meaning NO! She accepts a male by flipper waving and pushing. They mate and she continues the cycle. There may be one or more matings per year. They lay from 6 to 7 times 100 eggs at one time.
The baby turtles or nestlings dig out from 30 to 72 days after the eggs have been laid. They come out at night to avoid heat and sun and predators. Some of their predators that eat the eggs include: raccoons, foxes, coyotes, dogs, and man. Predators that eat the hatchlings include: rats, cats, snakes, lizards, gulls, and herons. Those that make it to the sea are eaten by carnivorous (meat eating animals) fish and crabs. Those that grow up are eaten by sharks, man, dogs, and jaguars (jaguars eat the nesting moms). Approximately 1% of all the eggs laid by sea turtles become adults.
Most sea turtles are endangered species because their nesting grounds have slowly been destroyed by mankind. The Green sea turtle is hunted for food, and the Hawksbill is hunted for their shell.
Adult sea turtles feed mostly on water plants, like seaweed and sea grasses near coastlines. They also eat small crabs and jellyfish. Some adults prefer octopus and squid. Newly born turtles are believed to feed on plankton the first year of their lives. Sea turtles live to be very old, approximately 100 years or more. They may be the first air breathers to move back to the sea, maybe 200 million years ago.
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"The life of a turtle is very hard." |
Spain is a country in the south of Europe and has a variety of landscapes. In the middle of Spain there is the central plateau, which is a harsh and barren area. But around that plateau lies the Central Sierras, which are famous for its skiing possibilities. The east coast is famous for its tourism, and many North Europeans go there in the summer to enjoy the warm weather.
The starfish is related to the sand star and the sea urchins, all together they are called Echinoderms.
Echinoderms contain approximately 5300 marine species, including sea lilies, sea stars, sea cucumbers and sea urchins. Echinoderms are all saltwater animals and have been around for about 600 million years. They are invertibraes, have radial symmetry with 5 arms or petals. Then have an endoskeleton of calcareous nodules called "ossicles". They are covered by an outer skin with small hairs or "cilia". They have a unique water circulation system, and their feet, called "podia" are used for respiration, movement and feeling.
Starfish belong to the class Asteroida and are found in all oceans from the polar areas to the equator, but prefer rocky coasts. They have five arms around a central disc. A sieve plate called "porite" is usually brightly colored and found on top of the starfish. It is used to take in water. It's water circulation or vascular system has a tube-like ring around the central portion with "radial canals" extending from the central ring down each arm. Their tube feet or podia are connected to the radial canals. Small sacs called "ampullae" are connected to the podia. The contraction of the ampullae force water into the podia. This helps the animal to move and capture food. The mouth is located underneath the starfish in the center. Starfish are carnivores. They like clams, oysters, and snails the best. When a starfish eats a clam or oyster, it grabs the shell with its podia and exerts pressure. It can do this because of its vascular system. This helps the starfish to hold on for a very long time, and the oyster or clam eventually gives up and is eaten by the starfish. The starfish can also invert its stomach and find a weakspot in the shell. It then starts digesting the clam or oyster until it opens its shell., exposing itself to a tasty dinner for the starfish.
Two of the five classes of the order Echinodermata, the Holothurians (sea cucumbers) and Echinoideas (sea urchins), include species which are the bases of valuable export fisheries, and are widely used artisanally. Sea urchins have globular bodies covered by a shell or test with the mouth directed downwards towards the substrate, and the anus directed upwards. The movable spines of sea urchins vary between species. The pin like spines of the tropical hat-pin urchin, "Diadema", reach lengths of over 30 cm, and contain toxins capable of inflicting a painful wound. The spines of the slate-pencil urchin, "Heterocentrotus", on the other hand, are blunt, and are adapted for wedging the animal into crevices on coral reefs.
Sea urchins feed on algae and small animals using a specialized apparatus called Aristotle's lantern (in honor of the Greek naturalist and philosopher).
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Sunbathing starfish |
Submarines ("the Iron Fish")
Submarines are boats which can travel under the surface of the water. Usually these boats are used by the military (the navy). Sometimes submarines are used by scientists to go under the surface of the water to explore the deep, dark sea and its mysteries. Submarines have "periscopes", which are used to look above the surface of the water.
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The Iron Fish |
Swell
When a group of waves made by the wind moves away from storms, they become more even and gentle and then they are called swell. These are high, long waves, fairly evenly spaced that travel long distances across oceans. They can do this because of the energy given to them by the winds. The stronger the winds, the farther these waves can travel. These groups of waves traveling together are called a "wave train". As the wave train moves over a larger and larger area of the ocean, they spread their energy and loose some of their height, but maintain their length. These waes eventually loose their energy and die, or they crash on some fa distant shore. Waves made by storms in Antarctica can travel to Alaska.
Temperature
Temperature is the determination of how hot or cold an object is, and, in this case, it is the measure of how hot or cold the oceans are and where they are hot or cold. It is the most important property of seawater and the most measured by scientists. The distribution of life, the plants and animals, all depend on temperature. The temperature of the oceans moderates the climate so that most of the Earth is a comfortable place to live. The extreme areas are the poles and the equator. The poles are very cold and the equator is very warm. The rest of the Earth falls somewhere in between.
The continents and oceans of the Earth are heated by the sun. Because the sun's rays fall more directly on the equator than on the poles, it is warmest there. The Earth is divided into three zones according to temperature. They are the tropical zone, the temperate zone, and the polar zone. The tropical zone is located around the equator. The average ocean temperature is near 25°C (78°F) and does not change much throughout the year. The temperate zone is located between the tropic and polar zones in each hemisphere. The average ocean water is 10°C (50°F) and varies between 9°C (40°F) ) and 15°C (60°F) depending on the season. The North and South Poles are in the polar zone, and the average temperature is around 3°C (27°F). Like the equator, the temperature does not change very much throughout the year. Both the North and the South Poles are ice covered in winter and summer.
The ocean is able to store heat more efficiently than land. The ocean does not have large differences in temperature between winter and summer like continents do. For example, in the temperate zone of the Atlantic Ocean, the seawater temperature might vary 15°. The winds and the ocean currents transport heat towards the equator. This helps to balance the distribution of heat over the Earth.
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Hot and cold |
Tide
Every day the oceans have two high and two low tides. This means that when it is high tide the ocean is at its highest point, and when it is low tide the ocean is at its lowest point. When you are on a beach you can see this very clearly. When it is low tide the beach is very wide, and when it is high tide the beach is very small.
Tides are waves caused by the gravitational pull of the sun and the moon. The greater force is the moon because it is closer. The tide waves affect and move the entire ocean. High tide is the crest and low tide is the trough of the wave.
You may notice when you go to the beach that the height of the tide is a little different each day until it reaches its highest point and then will decrease each day until it reaches its lowest point only to start increasing again. These highs and lows cycle on a monthly basis with the phases of the moon.
A bulge of water rises on the side of the earth facing the moon, and an equal bulge forms at the same time on the opposite side. This is because the forces generated by the rotation of the earth and moon around each other push the water outward. The sun reinforces or offsets the moon according to its position. When the sun and moon are in a straight line with the earth, the pull of each is added together, and we have our highest tides. These are called spring tides. This occurs during the new or full moon. When they are at right angles, the moon and sun cancel each other and we get out lowest lows. These are called neap tides. This occurs when the moon is in its first or third quarter.
The tides involve more than just the earth, sun and moon. Adding in complicating factors like the changing depths of the ocean bottoms, shapes of the continents and shorelines, islands, and the spinning of the earth will affect the tides. In fact, there are about 120 different possible affects on the tides. All this information is put into very complicated equations to calculate the tides.
The Tropics
This is an area on earth which is very humid and hot. When you look at a map of the world you can see the equator, a line that circles the earth in the middle. The area around the equator is the area which is called the tropics. The land that lies on the equator is mostly covered with a tropical rain forest. This forest is rich of animals, and in Brazil the rain forest is inhabited by Indians.
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Temperature Zones |
United States of America
The United States of America is the strongest political and military power in the world. We have seen this many times in the past. For example, during the Gulf War in the Middle East the US contributed most of the military equipment and personnel.
The US has various landscapes: tropical in Southern Florida, deserts in Arizona and New Mexico and the north-eastern part has to deal with blizzards in the winter.
The people who live in the US are all descendants from Europeans, except for the Native Americans (the American Indians) who already lived here when the white people came. The United States are divided in 50 states.
Upwelling
Upwelling in coastal areas are caused by winds blowing parallel to the shore. Because of the earth's rotation, the waters will move to the right of the wind direction in the Northern hemisphere. As the surface waters move offshore, they are replaced by deep ocean water moving up the continental slope with plenty of nutrients.
A large upwelling off the Pacific coast of South America is caused by Coriolis force acting on a strong northerly Humbolt current. This force causes the current to veer away to the left, shore line surface waters are replaced by an upwelling of deeper water. This upwelling results in rich fisheries off the coast of Peru.
An equatorial upwelling in the western Pacific results from two currents (the north and south equatorial currents) moving apart, one northwards towards Japan and the other southwards down the coast of Australia. As these two currents move apart, deep nutrient-rich water moves up to replace surface waters in the region of the equator.
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Vectors are symbols used by scientists and mathematicians to represent the direction and speed of an object. For example, they can represent ships crossing the ocean, cars driving on the highway, or airplanes flying in the sky.
Oceanographers use vectors to represent the speed and direction of a current. Sometimes scientists also use vectors to represent temperature. The vectors are placed on oceanographic charts for scientists to study and for ships to chart their course by. In fact, a Captain of a ship uses current charts like the driver of a car would use a road map. Meteorologists also use vectors to represent the speed and direction of the winds. |
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In the chart shown, vectors are used to show the direction and speeds of the shelf water, slope water, Gulf Stream, and Sargasso Sea. (Shelf water is the water that is over the continental shelf; slope water is water from the edge of the shelf, over the continental slope to the very deep ocean.) You do not see any vectors in the Sargasso Sea, because the currents there are to slow and to weak. The vectors would be so thin that they would be invisible. The vector in the Gulf Stream is large, because the Gulf Stream is a very fast current, and its direction is to the northeast. The vectors in the slope water are thin which shows us that the currents are weak and very slow. The vectors in the slope water change direction showing that the water moves along a circular path. The vectors along the coast show that the water moves slowly to the southwest.
A scientist might use this information to study where pollutants would go if they were dumped in the water. Since the Gulf Stream is a warm current, they could study how heat is carried to the north and how it affects the weather off the East Coast of North America. A ship captain going to England from the United States would sail the boat to the Gulf Stream to help the ship move faster across the ocean.
Wake
The wake of a boat is the sucking stream behind the boat. This sucking stream is created by the boats engines and is very powerful. If a person should fall in this wake he will get sucked under water and he can get caught between the screwpropellers of the boats engine.
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The tail of a ship |
Walruses
Walruses are marine mammals and are further divided into the Pinnipeda. They are close relatives of the seals and sea lions. They have lost their tail, and their hind legs have developed into flippers for locomotion. They live in the cold, arctic waters. These animals are very large and have a thick layer of fat or blubber under their skins to keep them warm, protecting them well against the ice cold. The male walrus grows between 3 and 4 m and weighs 1.5 tons. The female grows to 2 to 3 m and weighs around 1 ton. They swim at 6 to 8 kph (4 to 5 mph). The males have raw mustaches and long corner teeth made of ivory. These teeth can grow to be about 1 meter long and are used to defend themselves, to loosen shells, and to pull themselves onto land. Their body is gray and almost hairless. They live in the Arctic, and they are eaten by Polar Bears and Killer Whales. The Arctic natives use all parts of a walrus. The flesh is used for food; the blubber, for heat and light in the winter; the skin, for boat coverings; and the intestines for window covering.
The walruses come together on the coast to reproduce. Their blubber provides buoyancy, padding, and reserve energy for the female when she is nursing her young and for the male who fasts when establishing a harem. Like most marine mammals, they generally have one pup per female. It is hard for a sea mammal to protect and feed more than one pup at one time. Their milk is very rich and nutritious and contains about 42% fat. The purpose is to produce the protective blubber in the young at a rapid rate to strengthen them for swimming.
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The Walrus family |
Water cycle
| When the sun heats up the water from the ocean, the water evaporates and rises to the atmosphere. When the atmosphere is filled with very much water, clouds are formed. When these clouds get heavy with water, they form rain and fall to the earth. This rain falls into the ocean or on land. When rain falls on land it will form rivers and eventually flow into the sea. |
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Waves
A wave is a bump on the water that moves through the ocean. The waves in the story are generated by the winds blowing on the water. These are called wind waves. The height and speed of the waves depend on the strength and duration of the winds. The waves in the area of the storm are called sea. The horizontal area of the storm over which the winds blow is called fetch. The winds are of constant speed and direction. As the waves move away from the storm area, they are called swell. These waves become smoother and after a while form a wave train: the waves then lose some height and increase in length. They move in the Pacific at around 65 kph (35 mph). Wave trains can go for thousands of miles. Waves generated by storms in Antarctica can wash ashore in Alaska. When they hit the shore, they are called surf.
The top of the wave is called the crest and the bottom is called the trough. The wave length is measured from crest to crest, and the wave height is measured from trough to crest. Particles in the waves do not move with the wave. A cork will bob up and down as the wave passes under it. Waves will grow to 1/7 the distance between crests without white caps. When you see a white cap, this is either the wind blowing the top of the wave off, or the wave is toppling over the store.
In narrow bays waves cannot build up to more than a few feet high. In the open sea, waves can grow very big. The height of a wave is approximately 1/2 of the wind speed. In a storm with 128 kph (80 mph) winds, waves may reach 12 m (40 ft). The largest wave recorded by a ship was 33.6 m (112 ft) in the pacific. Waves can grow by two or more combining.
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Surf's Up |
Whales
Whales belong to the order of Cetacea in the class of marine mammals. Most whales live in small groups called pods or alone near the coast or in bays or inlets. They live in all the great oceans on earth and are now a protected species. Whales move by using their tail flukes. Flukes are horizontal and did not come from the original boned tails of land mammals. Flukes are made of flesh, skin, and muscle. There are 2 groups of whales: the whalebone whales and the Toothed whales. The Whalebone whales are also called the Baleen whales. These mammals have 800 or more plates of baleen or whalebone hanging from the roof of their mouth. hey eat by straining their food from the water that is taken into the mouth and forced out through the baleen plates. Small creatures such as Krill (small crabs) and small schooling fish stick to the plates. The whale then swallows his dinner. These whales also eat lots of plankton. Baleen whales have 2 blowholes.
The toothed whales have teeth that range in a number from 2 to 250. They have only 1 blowhole. These include the Dolphin, Porpoise, Sperm whale and Killer whale. They eat animals such as squid, lobsters, and seals. These whales became whales about 20 million years ago.
The whale family contains some of the largest creatures in the world. The blue whale is the largest and is 30 m (100 ft) long and weight 150 tons. A dinosaur, by comparison, weighed about 30 to 35 tons. Larger whales travel 3 to 4 knots and may reach speeds upto 12 knots.
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Splashing whale |
Winds
Winds are generated across the earth's surface by pressure differences in the atmosphere. On the earth's surface there are bands of high and low pressure areas. The winds blowing from high to low pressure areas across the earth create forces on the sea's surface in the direction of the wind.
Windvector
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A Windvector is the same as a Vector that oceanographers use. When meteoroligists talk about winds, they describe the direction the winds are coming from.
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Zooplankton
Small floating animals and the larvae of large animals are collectively called "zooplankton". Zooplankton live at different depths in the sea. They can swim, and then move up into the surface layers during the night to graze on the phytoplankton. During the daylight hours, the zooplankton swim down to the deeper layers. This enables the phytoplankton to increase their numbers by cell division. Zooplankton are called secondary producers and are eaten by larger zooplankton, squids, and baleen whales.
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At the Zoo |
