Presentation on theme: "Oceans S6E3. Students will recognize the significant role of water in earth processes. a. Explain that a large portion of the Earth’s surface is water,"— Presentation transcript:
1 OceansS6E3. Students will recognize the significant role of water in earth processes.a. Explain that a large portion of the Earth’s surface is water, consisting of oceans, rivers, lakes, underground water, and ice.c. Describe the composition, location, and subsurface topography of the world’s oceans.d. Explain the causes of waves, currents, and tides.
2 OceansS6E5. Students will investigate the scientific view of how the earth’s surface is formed.f. Explain the effects of physical processes (plate tectonics, erosion, deposition, volcanic eruption, gravity) on geological features including oceans (composition, currents, and tides).
3 How are geological features that exist on land similar to those on the ocean floor? Terms to know:Sonar—sound navigation and ranging; system that uses sound waves to measure distances; has enabled scientists to map much of the ocean floorContinental shelf—gently sloping shallow area of the ocean floor extending outward from the edge of a continent
4 How are geological features that exist on land similar to those on the ocean floor? Terms to know:Continental slope—steep incline extending beyond the continental shelf to the deep ocean floorAbyssal plain—smooth, nearly flat region of the ocean floorMid-ocean ridge—underwater mountain range that winds through the oceans
5 How are geological features that exist on land similar to those on the ocean floor? Terms to know:Trench—deep, steep-sided canyon in the ocean floorYou should remember mid-ocean ridges and trenches from our study of plate tectonics. How are these two features related?
6 How are geological features that exist on land similar to those on the ocean floor? Terms to know:Intertidal zone—the part of the ocean between the highest high-tide line to the lowest low-tide lineNeritic zone—the part of the ocean extending from the lowest low-tide line out to the edge of the continental shelfOpen-ocean zone—the deepest, darkest part of the ocean beyond the continental shelf
7 How are geological features that exist on land similar to those on the ocean floor? Questions to consider:Why has the deep ocean floor been explored only recently?Which statements are true about the ocean floor? Which are false?It is flat and sandyIt is rocky and unevenIt has the biggest mountains on Earth.It has deep canyons.
8 How are geological features that exist on land similar to those on the ocean floor? Questions to consider:What are the three zones which make up the open-ocean zone?Surface zoneTransition zoneDeep zone
9 What’s in the ocean water? It’s saltyTable salt, or sodium chloride, NaCl, is the most common salt, but other salts include magnesium chloride, magnesium sulfate, calcium sulfate, calcium carbonate and others
10 What’s in the ocean water? Salinity—total amount of dissolved salt in a sample of waterOn average, kg of ocean water contains about 35 grams of salt—we say 35 ppt (parts per thousand)
11 What’s in the ocean water? Factors affecting salinity
12 What’s in the ocean water? Effects of salinityIncreases density
13 What’s in the ocean water? Effects of salinityLowers the freezing point of water
14 What’s in the ocean water? Temperature variationsSun warms the ocean water at the surfaceSurface temperatures are warmer near the equator and lower as we move away from the equatorDeeper in the ocean, the temperature decreasesCold water is denser than warm water
15 What’s in the ocean water? Gases in the oceanGases are dissolved in ocean waterOcean organisms need oxygen and carbon dioxideSurface water has more oxygen because of photosynthesis, which cannot occur in deeper waterCold water dissolves more oxygenDeeper water contains more carbon dioxide
16 What’s in the ocean water? Changes with depthTemperature decreases as you go deeper in the ocean; average temperature in the deep zone is 3.5 °CPressure increases with depth
31 What causes tides?Tides—the daily rise and fall of Earth’s waters on its coastlinesHigh tide—when the water reaches its highest pointLow tide—when the water reaches its lowest point
32 What causes tides?Tides occur regularly—two high tides and two low tides each day (about every 25 hours)Each high tide occurs about every 12 ½ hours; each low tide occurs about ½ way betweenTides occur in a cycle—high tide then low tide then high tide…
33 What causes tides?Tides are caused by the gravity of the moon pulling on Earth’s waters
34 What causes tides?The moon’s gravity causes a tidal bulge of water on the side of Earth closest to the moon; the waters on the other side are “left behind” and create a second bulge
35 What causes tides? The sun is also involved in tides Two special tides occur each month because of the sun’s gravitySpring tides and neap tides
36 What causes tides?Spring tide—the greatest difference between high and low tideHigh tides are their highest; low tides are their lowest
37 What causes tides? Spring tides The sun’s gravity combines with the moon’s gravityOccur at new moon and full moonSun, Earth and moon are in a straight line
38 What causes tides?Neap tide—the least difference between high and low tideHigh tides are lower than usual; low tides are higher than
39 What causes tides? Neap tides The sun’s gravity competes with the moon’s gravityOccur at 1st and 3rd quarter moonsSun, Earth and moon are at right angles
40 What causes currents?Currents—large streams of moving water that flow through the oceansTypes of currentsTidalSurfaceDeep
41 What causes currents?Surface currents—affect water to a depth of several hundred metersDriven mainly by windsMove in a circular pattern
42 What causes currents?Why do currents move in a circular pattern?
43 What causes currents? Why do currents move in a circular pattern? The Coriolis effect—the effect of Earth’s rotation on the direction of winds and currentsDoes the Coriolis effect work the same all over the Earth?
44 What causes currents?Does the Coriolis effect work the same all over the Earth?Currents in the Northern Hemisphere curve to the right, or clockwiseCurrents in the Southern Hemisphere curve to the left, or counterclockwise
45 What causes currents?Surface currents warm or cool the air above them, influencing the climate of the land near the coastCurrents affect climate by moving cold and warm water around the globe
46 What causes currents?The Gulf Stream is the largest and most powerful surface current in the North Atlantic Ocean. It carries more water than the Mississippi!
47 What causes currents?Does the Gulf Stream carry warm water or cold water?(hint: look at where it originates)
48 What causes currents?The warm waters of the Gulf Stream bring a mild climate even to areas near the Arctic, such as Norway
49 What causes currents?The Gulf Stream is a warm water current, originating in the warm waters of the Gulf of MexicoCurrents which flow from waters near the equator toward the poles are warm currentsCurrents which carry water from the poles toward the equator are cold currents
50 Can you tell which currents are cold currents and which are warm currents? Notice the Coriolis Effect—which curve right and which curve left?
51 What causes currents?El Niño is abnormal climate event that occurs every 2 to 7 years in the Pacific OceanUnusual pattern of winds in the western Pacific pushes a huge amount of water toward the South American coastUnusual weather patterns around the world
52 What causes currents?Deep currents move water at greater depths, even along the ocean floorMove much more slowly than surface currentsAlso called thermohaline currents
53 What causes currents? Deep currents, or thermohaline currents Caused by differences in density, due to temperature and salinity variationsWhat factors affect ocean water temperatures?What factors affect salinity?
54 What causes currents?Factors affecting salinity
55 What causes currents?Deep currents move and mix water around the world. They carry cold water from the poles toward the equator.
56 What causes currents?Upwelling—the upward movement of cold water from the ocean depths to replace warm surface water moved away by windsBring up ocean organisms, minerals, and other nutrients from the deepWithout upwelling, surface waters would have little nutrients
57 Scientists have used accidents to track currents In 1992, a cargo ship lost several containers during a violent storm in the Pacific
58 Scientists have used accidents to track currents One of the containers broke apart—it was carrying thousands of toy ducks!
59 What have I learned about the ocean? Subsurface topography (features of the ocean floorSalinity and factors affecting itCauses of ocean waves and parts of a waveCauses of tides and how special tides occurCauses of currents, surface and deep, and how they affect climate