Ocean Motion Met 101: Introduction to the World's Oceans Produced by The COMET Program Geography: Name Pd. Earth s oceans covers 71 % _ of the planet s surface. In reality, Earth s ocean waters are all interconnected as part of a single large global ocean. List the five oceans in order from largest to smallest Name Size (sq km) 1. Pacific Ocean 168,723,000 2. Atlantic Ocean 85,133,000 3. Indian Ocean 70,056,000 4. Southern Ocean 21,960,000 5. Arctic Ocean 15,558,000 Ocean Circulations: Currents are cohesive streams of seawater that circulate through the oceans. Currents are caused by wind, gravity, and variations in water density. A gyre is a well-organized, circular flow of ocean currents. Currents curve or bend as a result of a phenomenon called the Coriolis effect. Rip Currents form where obstacles channel water away from the shoreline. Upwelling brings cold, nutrient water to the surface that promotes plant and animal productivity. In the word thermohaline, Thermo = temperature and Haline = salinity. Currents play an important role in the Earth's climate system. Overall, ocean currents moderate the planet's temperature extremes. Warm flows, like the western boundary currents, carry heat from the tropics toward the poles. 1
Global Wind and Ocean Currents moves energy around our planet. The movement of this energy around the world is what gives places certain climates and weather. 2
After labeling and coloring the currents on the map, answer the following questions. 1. When the oceans are referred to as having a conveyor belt, what is being conveyed or moved around? The water is moving. 2. Explain why ocean water is warmer in some parts of the world than in other s. At the Equator the Sun s rays are stronger so the water there is warmer At Earth Poles the Sun s rays are weaker so the water there is cooler 3. The ocean currents on your map generally travel in either a clockwise or counterclockwise direction. Look at the ocean currents and compare and contrast the general direction of the currents in the Northern Hemisphere with those in the Southern Hemisphere. In the N.H. the currents travel Clockwise In the S.H.the currents travel Counterclockwise 4. Cold-water currents tend to have a cooling effect on the continental coastlines that they border, while warm-water currents tend to have a warming effect. a. As a result of the ocean currents in the Northern Hemisphere, which coastlines are going to experience a warming effect and which a cooling effect? East coast of a continent's coastline will have a warming effect where the west coast of a continent will have a cooling effect. b. Look at the pattern of currents in the. As a result of the ocean currents in the Southern Hemisphere, which coastlines are going to experience a warming effect and which a cooling effect? _ West coast of a continent's coastline will have a warming effect where the east coast of a continent will have a cooling effect. 5. Look at the pattern of cold- and warm-water currents. What seems to determine whether a current carries warm or cold water? Where the current comes from. Poles = cold, Equator = Warm 3
Wind Waves and Swell: Wave Height = - The wave height is the difference between a wave s highest point, or crest, and its lowest point, or trough. Wavelength = - A wavelength is the distance from crest to crest. Period = - The wave s period is the time it takes consecutive wave crests to pass a given point. Characteristics of Ocean Waves: Most waves are caused by wind. As a wave moves through the water, the surface of the water rises and falls. The highest part of a wave is referred to as the crest : the lowest part is called the trough. The wave height is the difference between two successive crests or troughs. The time required for two successive crests or troughs to pass a certain point is referred to as the wave period. Wave speed can be calculated using the following relationship. When waves move into shallow water, the troughs begin to drag along the bottom and slow down, while the crests continue at their normal speed. As a result, the front of the wave becomes steeper than the back of the wave. Eventually, the crest topples over and the wave is said to break. Waves break in water that has a depth equal to approximately one-half the wavelength or about 1.3 times the wave height. Equations: ½ Wavelength = Wave Break or 1.3 Wave Height = Wave Break 4
Use this information and the following diagram to answer questions 1 through 4. 1. In the diagram above, label the wave crests and wave troughs on the diagram. 2. What is the wavelength? 6 m 3. What is the wave height? 2 m 4. What is the speed of the waves is the wave period is 4 seconds? Show your work. Wavelength / Wave Period = Wave Speed 6 m / 5 sec = Wave Speed 3 m/sec = Wave Speed 5
Use the background information and the following diagram to answer questions 5-8. 5. Using the equation ( ½ Wavelength = Wave Break ), in what depth of water would a wave begin to break if it had a wavelength of 3 meters? ½ Wavelength = Wave Break ½ 3 m = Wave Break 1.5 m = Wave Break 6. Using the diagram above and your answer from question 5, how far from the shore would a wave break that had a wavelength of 3 meters? 6 meters from the shore 7. Using the equation ( Wave Break ⅓ = Wave Height ), what would the wave height be for the wave described in the previous two questions? Show your work. Wave Break ⅓ = Wave Height 1.5 m ⅓ = Wave Height 0.5 m = Wave Height 8. If the increased winds caused an increase in wave heights, would the distance the wave break from the shore increase or decrease? Show proof to your answer. Increase: Wave Break ⅓ = Wave Height Wave Break ⅓ = Wave Height 3 m ⅓ = Wave Height 1.5 m ⅓ = Wave Height 1 m = Wave Height 0.5 m = Wave Height 6
Tides Tides are regular changes in ocean water levels caused by the gravitational pull of the: moon Earth sun There are two high tides and low tides each day, with six hours separating each high tide from the next low tide. The change from high tide to low tide is called an ebb tide. Though the gravitational pull of the Sun on Earth is much stronger than the gravitational pull of the moon, the moon s close proximity makes its tidal influence more than double the influence from the Sun. - Spring Tide and Neap Tides: Tides are stronger than normal when the moon is new or full. At these times, the moon is in line with the Sun and Earth, and the Sun s gravitational pull works in conjunction with the moon s pull to cause higher high tides and lower low tides. These stronger than normal tides occur twice during each 29-day lunar cycle and are called spring tides, or in many Pacific Ocean locations, king tides. At the moon s quarter phases, the Sun and moon are not in line with Earth, and the Sun s pull acts against to that of the moon. Tides during these times are weaker than normal, and are called neap tides. 7
8
9
10