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ocean water ocean water Presentation Transcript

  • 1. Learn the origin of the waters in Earth’s oceans 2. Explain how dissolved salts and other substances get into seawater 3. Describe the composition of seawater 4. Determine how surface currents are influenced by winds, the Coriolis effect, and continents 5. Explain why waters off the western coasts of continents are usually colder than waters off the eastern coasts of continents 6. Describe how density currents cause ocean water below the surface to circulate 7. Describe the parts of a wave 8. Diff. between the movement of water particles in a wave and the movement of wave energy 9. Describe how waves are created by the energy of wind and the gravitational force of the moon and sun
  • Do this simple activity to discover how currents work. Fill a large beaker with warm water. You could also use a pan of water instead of a beaker. Gently add a drop of food coloring at the center. Now carefully float an ice cube at the center. After a minute, what happens to the food coloring? Add two drops of food coloring directly on the ice cube to help you see what is happening . You have just made a density current.
  • The ocean is influencing you right now, no matter where you live. If it is raining or snowing today, most of that water came from the ocean. If today is sunny, it is partly due to weather systems that developed over the ocean. If you eat fish today, it most likely will have come from the ocean.
  • Oceans also affect the prices charged for clothing, cars, and gasoline. The price includes the cost of shipping those materials across a great barrier, the ocean. If you live near a stream or river that is polluted, that pollution eventually will travel to the ocean. The ocean grately affect your life.
  • • In the first billion years after Earth was formed, its surface was much more volcanically active than it is today. • About 4 billion years ago, this water vapor began to accumulate in Earth’s early atmosphere. It eventually cooled enough to condensed. Precipitation began to fall onto Earth. Earth’s oceans were formed over millions of years as this water filled low areas on Earth called basins.
  • • Oceanographers have learned that the ocean contains many dissolved elements, including sodium, chlorine, silica, and calcium. • Where do these elements come from? One source is ground water, which very slowly dissolves elements such as calcium from rocks and minerals. The calcium is then carried by rivers into the ocean. Another source is the volcanoes that erupt, releasing gases into the ocean.
  • • The two most abundant dissolved elements are:  Sodium – dissolved in river water that flows into the ocean.  Chlorine gas – added by volcanoes. • When sodium and chlorine are combine in the seawater, they form a salt called halite. • Nearly 90% of the salt in seawater is made of sodium and chlorine.
  • 96.50 % 3.2% Ocean Water Water Salts 1.10% 1.20% 2.50% 3.70% 55.20% 30.50% 5.80% Elements making up salts in Ocean Water Potassium Calcium Sulfur Magnesium Chlorine Sodium Others
  • • Every 1,000 L of ocean water contains about 35 L of dissolved salts, or 3.5%. • Salinity is a measure of the amount of solids dissolved in seawater. • The salinity of the ocean has stayed about the same for hundreds of millions of years. This tells us that the ocean’s composition is in balance.
  • In some areas that have little fresh water, salt is removed from ocean water. Saudi Arabia, which borders the Red Sea and the Persian Gulf, for example, makes fresh water from salt water using a desalination system. Desalting ocean water can be done in several ways. In one method, salt water is boiled and the steam is piped into a container where it cools. As the steam forms, the salts are left behind and fresh water is produced.
  • In another method, permeable membranes and an electric current are used to separate the salt from the water. Membranes that allow only negative ions to pass. The electric current is then to further separate the ions to produce fresh water. In a third method of desalination, ocean water is frozen. The salt crystals are separated from the ice crystals by washing the salt from ice with fresh water.
  •  • Surface ocean currents, just like surface winds, are influenced by the Coriolis effect. • Coriolis effect – the effect of Earth’s rotation on the movement of air masses. • The Coriolis effect causes most currents north of the equator to move in a clockwise direction. Most currents south of the equator always move in a counterclockwise direction.
  •  • Another factor that controls currents is the continents that deflect currents. For example, in the Pacific Ocean, currents moving toward the west are deflected northward by Asia and southward by Australia, which deflect them toward the equator. • Surface currents are important because they affect the climate of places they pass by.
  •  • A density current occurs when denser seawater moves toward an area of less dense seawater. • Denser water around the North Pole and the South Pole sinks and travels along the ocean floor toward the equator. At the same time, less dense water at the equator rises and moves toward the poles along the surface. These two events form a continuous cycle that circulates ocean water.
  •  • What can make seawater denser and sink? The cold air near the poles chills the water, causing its molecules to be less active and closer together. This decrease the volume of the water and makes it denser, so it sinks. Also, the cold climate freezes some of the water. This concentrates the salts in the remaining unfrozen water, which increases its mass, makes it denser, and causes it to sink. Once this happens, the colder, saltier, denser water moves as a mass along the ocean bottom.
  •  • Waves are caused by winds, earthquakes, and the gravitational fore of the moon and sun. • Waves are movements in which water alternately rises and falls. • Parts of a wave:  Crest – the highest point of the wave.  Trough – the lowest point.  Wave height – the vertical distance between crest and trough.  Wavelength – the horizontal distance between the crests of two successive waves or the troughs of two successive waves.
  •  • Two different types of waves:  the common sea waves caused by the wind  the long waves of the tides.
  •  When wind blows across a body of water, friction causes the water to be moved along with the wind. If the speed is great enough, the water begins to pile up, forming a wave. As the wind continues to blow, the wave increases in height.  Waves stop forming when the wind stops blowing. But, once set in motion, waves continue moving for long distances. Waves you might see at a seashore originated many kilometers away. The height of waves depends on the speed of the wind, the distance over which the wind blows, and the length of time the wind blows.
  •  • Tides - The periodic change in the surface level of the oceans due to the gravitational force of the sun and moon on Earth. • Gravitational force is an attractive force that exists between all objects. The strength of gravity is affected by the masses of objects and fall by a few meters twice a day. The tidal range is the difference between the high tide and low tide.
  •  • The moon and Earth are relatively close together in space, so the moon’s gravity exerts a strong pull on Earth. The gravitational force of the moon is stronger on the side of Earth that is facing the moon. The moon’s gravity pulls in water particles in the ocean and causes the water to bulge on the side toward the moon and on the side opposite the moon. • These bulges of water on both sides of Earth are waves that we call high tides when high tides form, water is drawn away from the areas between the bulges, creating low tides at those places.
  • • The sun also affects tides. The sun can strengthen or weaken the moon’s effects. When the moon, Earth, and sun are lined up, high tides are higher and low tides are lower than normal. These are called spring tides. When the sun, Earth, moon form a right angle, high tides are lower and low tides are higher than normal. These are called neap tides.