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  • 1. CHAPTER 3 SEAWATER: ITS MAKEUP AND MOVEMENTS
  • 2. Rain Snow Purest sources of water: 1 ~ Snow 2 ~ Rain
  • 3. Most materials expand when heated and contract when cooled. Water: ~ contracts until cooled to 39.2° F (4° C) then ~ expands rapidly as it freezes at 32° F (0° C) and ~ increases in volume about 9%
  • 4. Without expansion, ice would sink. Water would freeze from the bottom up. Evolution would have been different. Expanding ice floats, serves as an insulation barrier, and holds heat in the water below.
  • 5. The vast world ocean: • Enormous heat-controlling thermostat • Absorbs and loses heat more slowly than land • Currents transfer heat to other areas
  • 6. Gary, Indiana ~ cooler in summer ~ warmer in winter Near coasts or Great Lakes, people know that near the water it is:
  • 7. Water is not compressible except in the extreme pressure of depth or laboratory. It cannot be made smaller in cubic volume.
  • 8. Water can “turn over” allowing warmer and colder waters to exchange depths (convection). Water can also evaporate from the surface aided by wind and wave action.
  • 9. Seawater’s ability to transmit light is fundamentally important to life in the oceans.
  • 10. Chemically, seawater is very pure, more than 95% water (hydrogen and oxygen). The remaining 5% contains about 80 elements in solution or suspension.
  • 11. Seawater Elements 5% Other Elements 95% Hydrogen and Oxygen O H2
  • 12. Seawater Elements which is common table salt. The 5% not Hydrogen (H) or Oxygen (O) is mostly Sodium (NA) or Chloride (CL),
  • 13. Some parts of the Red Sea in the summer have salinities as high as 41.
  • 14. The Great Salt Lake in Utah and the Dead Sea of Israel have salinities of 250 and 350 parts per thousand (ppt), the highest salt content on Earth.
  • 15. Every year, 80,000 cubic miles of seawater are drawn off by evaporation and condensation. 24,000 returns to continents as rain, sleet, and snow.
  • 16. The cycle of evaporation and condensation that controls the distribution of the Earth’s water as it evaporates from bodies of water, condenses, precipitates, and returns to those bodies of water Hydrologic Cycle (a.k.a. Water Cycle)
  • 17. Plants on land also add to the amount of water vapor entering the air in a process called transpiration.
  • 18. Today, only magnesium (Mg) and bromine (Br) are taken commercially from seawater. A full one-third lighter than aluminum, magnesium is used to manufacture lightweight alloys for airplanes and satellites. Bromine is used in the oil/gas drilling industry and, in combination with other elements, to manufacture flame retardants.
  • 19. Research is constantly under way to develop profitable ways to extract dissolved minerals from the sea.
  • 20. This is the area of oceanography and metallurgy that will undoubtedly expand as continental mineral resources are used up.
  • 21. Upper ocean water temperature varies from about 32° F in the polar regions to a high of 85° F in the Persian Gulf.
  • 22. (0° C)(-2.2° C) Salt lowers water’s freezing point. However, in the deep ocean bottom, water stays at a uniform temperature of about 4 °C (39.2 °F). 28° F 32° F FreshwaterSeawater
  • 23. bathy + thermo + graph depth temperature record Bathythermographs, commonly called BTs, are instruments used to check water temperatures at various depths.
  • 24. An instrument that makes a record of the temperature at various depths in the ocean Bathythermograph
  • 25. Navy XBT Most Navy combatants have expendable BTs (XBTs) to take readings.
  • 26. Fridtjof Nansen Nansen Bottle Nansen bottles are metal cylinders with automatic closing valves on each end that shut to collect water samples.
  • 27. A waterproof container for taking samples of ocean water, several usually being lowered open on a line and each being closed at the desired depth by the action of a falling weight Nansen bottle
  • 28. When valves close, a mercury column outside the bottle captures the temperature. After surfacing the samples, operators can test for salinity, chemical content, and minute marine life. Nansen Bottle
  • 29. In shallow places, ocean water appears light green, while in deeper water it seems to be blue, gray, or dark green.
  • 30. The Red Sea is so named because of red phytoplankton in the water.
  • 31. The Yellow Sea is so named because of the yellow silt carried into it by rivers in northern China.
  • 32. ULTRAVIOLET Sunlight consists of a range (spectrum) of different wavelengths of energy.
  • 33. Radiation with wavelengths longer than visible light but shorter than radio waves Infrared
  • 34. Radiation with wavelengths shorter than visible light but longer than X rays Ultraviolet
  • 35. Spectrum of Rainbow Colors Beam of White Light Prism Using a prism will display the visible spectrum.
  • 36. The atmosphere filter keeps out most of the dangerous ultraviolet rays. Water vapor and carbon dioxide absorb much of the infrared rays and blanket the Earth with life sustaining warmth.
  • 37. Water: ~ acts as a filter ~ scatters wavelengths starting at red end the deeper the water the greater the blue Below 90 feet: dark zone of blues, violets, grays, blacks, and nothing else
  • 38. Zone Comments Lighted Twilight Dark 3 to 330 260 to 655 Below 655 Life in the sea is bountiful No effective plant production No plants grow and animal life consists of carnivores and detritus feeders Depth (in feet) Ocean Light Environments
  • 39. Waves are caused by any energy source that disturbs the water surface.
  • 40. Any disturbance to a water surface will cause ripples. Tsunami waves (huge ripples) can travel thousands of miles across an entire ocean.
  • 41. Wind is the most common cause of ordinary waves. Sailors often call wind-driven waves “sea” or the state of the sea.
  • 42. Swells: may indicate an approaching storm are quite common before hurricanes
  • 43. A long wave on water that moves continuously without breaking Swells
  • 44. • Wind speed + Duration of wind + Length of fetch = determines wave height
  • 45. The distance over which a wind blows The distance traveled by waves with no obstruction Fetch
  • 46. Whitecaps begin at about 13 knots of wind.
  • 47. 12 to 15 foot waves ~ common during a strong storm
  • 48. 25 to 30 foot waves ~ may occur during severe storms or hurricanes
  • 49. Wave Terminology Wave height (H)
  • 50. Period past a given point Wave Type Wind Swell Tsunami Period 2 to 5 seconds 12 to 15 seconds 10 minutes to 1 hour
  • 51. Waves that break (fall over) when reaching a shallower bottom are called breakers.
  • 52. A line of breakers along a shore is a surf, or surf line. The slope of the bottom (gradient) determines the kind of breakers. There are three types.
  • 53. A spilling breaker develops where there is a mild, gradual, almost flat bottom shape. It can be seen advancing as a line of foam.
  • 54. A plunging breaker occurs where there is a steep bottom slope. Such a gradient creates huge surfs, like in Hawaii, that are the joy of surfers.
  • 55. A surging breaker occurs where there is a very steep bottom slope with rock formations such as along the coasts of Alaska and much of California.
  • 56. Knowledge of each is crucial to naval and marine amphibious operations. Sea Waves - Swell - Surf Conditions
  • 57. On an average beach, a 4-foot surf is considered the “critical” height for safe amphibious landings. Above that height, boats may broach, To veer or cause to veer broadside to the wind and waves .
  • 58. Erosion Local action of waves, tides, and currents shape coastal landforms.
  • 59. Erosion Rocky Outcropping
  • 60. People who have had the misfortune of having a beach cottage undermined or washed away during gales and hurricanes know what this means.
  • 61. Cape Cod, Massachusetts Waves and currents produced by waves cause most shoreline change. The U.S. coastline is eroding about 1 foot a year.
  • 62. However, in other places like the Mississippi River Delta, waves and currents build shoreline with sediment accumulation. New Orleans, Louisiana
  • 63. Carried by wave action, small fragments of rock and sand scour away beaches and wear down shoreline.
  • 64. When one part of the wave line develops drag and changes direction or bends in shallower water this is refraction, critical in amphibious assault landings. Waves align with bottom contours and conform to general slope of coastline.
  • 65. Engineers must account for local wave refraction to take advantage of it when designing protective structures.
  • 66. Most common harbor protection is a breakwater (line of big rocks) sometimes with steel-reinforced concrete.
  • 67. The protective structure of stone or concrete; extends from shore into the water to prevent a beach from washing away A barrier that protects a harbor or shore from the full impact of waves Breakwater
  • 68. Another common structure is a groin, walls of stone or wooden pilings built at right angles to a shoreline. Cape May, New Jersey
  • 69. Built in a series of two or more, groins help prevent erosion by damming sediment from longshore currents that occur at the immediate shoreline. However, groins may cause additional erosion in another location.
  • 70. Sandbars become navigational hazards.
  • 71. Rip currents are strong, seaward moving currents. They occur when opposing longshore currents meet.
  • 72. A strong, narrow surface current that flows rapidly away from the shore, returning the water carried landward by waves Also called rip tide, tiderip Rip Current
  • 73. Rip current and undertow are not the same forces. Undertow is the natural seaward and downward thrust of a wave as it breaks. Rip currents occur at the junction of opposing longshore currents. Some rip currents move at speeds up to 2 miles an hour.
  • 74. Rip currents: ~ rarely over 100 feet wide ~ swim parallel to the shore ~ don’t panic
  • 75. Ocean currents have profound effects on people, weather, and food cycles. Studying ocean currents can be complex.
  • 76. Earth’s atmosphere (winds) and oceans (currents) are linked.
  • 77. Gaspard de Coriolis The Earth’s rotation creates an invisible force called the Coriolis effect. Southern Hemisphere Northern Hemisphere Objects deflect to the left in the Southern Hemisphere The apparent deflection of moving objects relative to an observer on the earth Objects deflect to the right in the Northern Hemisphere
  • 78. The apparent deflection of particles in motion with respect to the Earth Caused by the rotation of the Earth Appears as a clockwise deflection the Northern Hemisphere, counter- clockwise in the Southern Hemisphere Coriolis Effect
  • 79. Two important factors affect global movement of wind and water: • Wind acting on water surface • Boundary effects of the continents
  • 80. The water level of the Sargasso Sea is 3 feet higher than along the west coast of the Atlantic Basin.
  • 81. Ocean current movement is a result of convection and surface wind systems. Of the two, surface wind has a greater role in effecting global water movement. Surface winds and landmass locations produce prevailing wind systems.
  • 82. In the Northern Hemisphere, prevailing winds are from the northeast from 0° to 30°.
  • 83. In the Southern Hemisphere, prevailing winds are from the southeast from 0° to 30°.
  • 84. Keep in mind: Winds ~ described by coming from. Currents ~ described by flowing to. Thus: A colonial sailor using Ben Franklin’s map to catch the Gulf Stream flowing NE, with prevailing winds (SW at 40° N Lat), could have following winds and a speedy trip. A NE current and a SW wind are headed in the same direction.
  • 85. United States Cuba Miami The most important current affecting the U.S. and Atlantic seaboard
  • 86. Warm ocean current of northern Atlantic Ocean off North America Originates in Caribbean, passes through Straits of Florida, flows northward along southeast United States veers northeastward at Cape Hatteras into Atlantic Ocean and splits to form North Atlantic Drift and Canary Current Gulf Stream
  • 87. An oval 2,000 miles E-W by 1,000 miles N-S, Sargasso Sea forms an oceanic desert with specially adapted plant life.
  • 88. Icebergs calving from Western Greenland Glaciers travel south on the Labrador Current into the North Atlantic shipping lanes. The north traveling Gulf Stream eventually melts them.
  • 89. The currents of the Gulf Stream and North Atlantic Drift warm the regional climate more than any other area at similar latitude.
  • 90. Late summer and early fall, the southern side of the Sargasso Sea Winds from West Africa blow over the warm currents of the Atlantic. Spawning Ground for Hurricanes
  • 91. Hurricanes often track the Gulf Stream into the Caribbean and Gulf of Mexico or up the East Coast of U.S.
  • 92. China Philippines Japan Indian Ocean South Pacific Ocean North Pacific Ocean Kuroshio Current
  • 93. Typhoons are the Pacific equivalent of Atlantic hurricanes, with the Western Pacific averaging 20 per year.
  • 94. China Japan Philippines Korea Similar to Atlantic hurricanes, Pacific typhoons follow the warm current running near land.
  • 95. The warm Kuroshio current meets the cold, south bound Oyashio current and turns East across North Pacific. Hitting the continent, it becomes the Alaska current traveling North and the California current moving South.
  • 96. Winds set major currents in motion with friction, but a counterforce of gravity and Coriolis effect (higher latitudes) often create opposite motion in deeper water.
  • 97. In 1955, Dr. John Swallow invented a floating under- water device (a Swallow buoy) to aid tracking of deep current flow. Dr. John Swallow
  • 98. Surface current and countercurrent vertical mixing bring rich nutrients upwards drawing large number of fish.
  • 99. Distinct layers influence underwater sound transmission, important in undersea warfare.
  • 100. The Moon Our closest neighbor
  • 101. A weaker but much closer influence, the Moon’s gravitational pull is the main force acting on the world’s oceans cycling the rise and fall of ocean tides.
  • 102. The periodic variation in the surface level of the oceans and of bays, gulfs, inlets, and estuaries, caused by gravitational attraction of the Moon and Sun, and occurring about every 12 hours Tide
  • 103. Moon Pluto Earth The pull of gravity is very small for small objects, but enormous for a planet, moon
  • 104. Gravity alignment and centrifugal force interact to create variable bulges in the Earth’s oceans.
  • 105. The Sun causes tides also, but with only about two-fifths of the Moon’s effect.
  • 106. As the Earth rotates, the new and full moons produce the high and low ranges of tides because the Moon and Sun are working together. These tides are called spring tides.
  • 107. Exceptionally high and low tides that occur at the time of the new moon or the full moon when the Sun, Moon, and Earth are approximately aligned Spring Tide
  • 108. As the Moon orbits the Earth, halfway between the spring tides (Moon aligns with Sun) are the neap tides when the gravitational pulls are not working together. These are tides of minimal differences.
  • 109. Tide that occurs when the difference between high and low tide is least; the lowest level of high tide Neap tides comes twice a month in the first and third quarters of the Moon. Neap Tide
  • 110. The ebb of a tide is the fall of the tide, that is, the moving of the tide away from the shore.
  • 111. Receding or outgoing tide The period between high water and the succeeding low water Ebb Tide
  • 112. The flood of the tide is the rise of the tide, or the flowing of the tide toward the shore to its highest point.
  • 113. Incoming or rising tide The period between low water and the succeeding high water Flood Tide
  • 114. High tides occur twice a day (every 12 hours 25 minutes) in most parts of the world - a high tide nearest the Moon and a lower high tide on the opposite side of the Earth.
  • 115. The Earth and Moon are not in a fixed position relative to each other. For any location on Earth to be directly opposite the Moon again, it takes 24 hours and 50 minutes. Therefore, high tides are 12 hours 25 minutes apart.
  • 116. Tidal flows are critical for ship personnel. They impact: ~ slack or tension in mooring lines ~ harbor and channel navigation ~ boat runs and schedules
  • 117. Tides in mid-ocean are measurable only with scientific instruments.
  • 118. Boston (12 feet ±) Bay of Fundy (50 feet +) Norfolk (<6 feet) Tidal ranges vary from location to location. In some cases, especially in high northern latitudes, ranges are extreme.
  • 119. High Tide Low Tide Spring tide at the Bay of Fundy often exceeds 50 feet.
  • 120. Island of Mont-St.-Michel, France
  • 121. Mont-St.-Michel is surrounded by 10 miles of sand at low tide, but when the 41-foot tide rises, the water moves shoreward at 210 feet per minute.
  • 122. The Inchon, Korea harbor encloses its piers with graving basins or docks that hold in the 40-foot tidal waters.
  • 123. A tidal phenomenon in which the leading edge of the incoming tide forms a wave (or waves) of water that travel up a river against the direction of the current As such, it is a true tidal wave (not to be confused with a tsunami). Tidal Bore
  • 124. Amazon River in Brazil Amazon River
  • 125. Hangchow (Tsientang) River
  • 126. Fjords in Greenland, Norway, Alaska, and Chile are examples. Dangerous tidal currents occur in other world locations with big inlets and narrow entrances.
  • 127. A long, narrow, deep inlet of the sea between steep slopes Fjord
  • 128. Currents rushing in fjords at 8 or 10 knots make it too dangerous for boats and ships to attempt passage. Alaska Greenland
  • 129. Tidal currents through Great Barrier Reef channels reach up to 10 knots.
  • 130. The French built the world’s first highly successful tidal plant on the mouth of the Rance River. A dam containing turbines spans the estuary. Rance River
  • 131. Rance River Deben
  • 132. As the tides rise, they spin the turbines that drive banks of generators. When the dam in the basin is full, water is released through sluice gates.
  • 133. For centuries, the Dutch have reclaimed land from the sea with dikes and pumps.
  • 134. The largest project was enclosing the Zuyder Zee.
  • 135. • Generates electricity by tidal flow • Creates freshwater lakes • Protects shoreline from North Sea • Reclaims land from the sea • Creates a coastal highway and connects isolated islands • Completed in 1978 across the Rhine, Meuse, and Scheldt Rivers Delta Estuary Plan
  • 136. Rotterdam Netherlands Rhine River Germany
  • 137. A.1. FALSE. Q.1. TRUE or FALSE. Pure water is composed of two (2) atoms of oxygen and one (1) atom of hydrogen.
  • 138. A.2. FALSE. Q.2. TRUE or FALSE. Plants and animals can live indefinitely without water.
  • 139. A.3. Solid, Liquid, and gas Q.3. Name the three forms in which water can exist.
  • 140. A.4. TRUE. Q.4. TRUE or FALSE. Water will only exist in the liquid state in a temperature range from 32 °F to 212 °F at standard sea level pressure.
  • 141. A.5. Sodium, hydrogen, oxygen, and chlorine Q.5. What are the major components of seawater?
  • 142. A.6. TRUE. Q.6. TRUE or FALSE. Sound travels faster in water than in air.
  • 143. A.7. Salinity Q.7. What is the term used to describe the dissolved salts in seawater?
  • 144. A.8. FALSE. Q.8. TRUE or FALSE. The bathythermograph was designed to measure the salinity of the water more accurately.
  • 145. A.9. Nansen bottle Q.9. What is the name of the instrument that captures salt water at depth?
  • 146. A.10. The Dead Sea between Israel and Jordan Q.10. What body of water has the highest salt content of any on Earth?
  • 147. A.11. The passage of water through a plant from the roots through the vascular system to the atmosphere Q.11. What is transpiration?
  • 148. A.12. Wind speed, duration of the wind, and length of the fetch Q.12. What three (3) principal factors does wave height depend?
  • 149. A.13. The slope or gradient of the bottom Q.13. As a wave moves ashore, what determines the kind of breaker it will become?
  • 150. A.14. Walls of stone or wood pilings built at right angles to a shoreline to prevent erosion by longshore currents Q.14. What is a groin, and what is it used for?
  • 151. A.15. A swimmer should swim parallel to the shore (across the current) since a rip current is rarely more than 100 feet wide. Q.15. If caught in a rip current, what should a swimmer do?
  • 152. A.16. The Coriolis Effect is the apparent deflection of a body in motion with respect to the Earth caused by the rotation of the Earth. In the Northern Hemisphere, this is to the right (clockwise direction). Q.16. What is the Coriolis Effect?
  • 153. A.17. Gyres Q.17. What do we call the circular system of currents that rotate clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere?
  • 154. A.18. The Gulf Stream Q.18. What is the most important current affecting the U.S. East Coast?
  • 155. A.19. The existence of countercurrents. He found that a strong undercurrent ran counter to the South Equatorial Current in the Pacific existed in the deep ocean. Q.19. What did Townsend Cromwell discover in 1952?
  • 156. A.20. The Moon Q.20. What is the main cause of the rise and fell (ebb and flow) of the ocean tides?
  • 157. A.21. Spring tides Q.21. What do we call tides when they are at their highest and lowest?
  • 158. A.22. Spring tides occur at new and full moons when the Sun, Earth, and Moon are aligned and the gravitational pull of the Sun and Moon are working together. Q.22. What phase(s) is the Moon in during the spring tides?
  • 159. A.23. Neap tides Q.23. What do we call tides whose range is less than average?
  • 160. A.24. 12 hours and 25 minutes Q.24. Approximately how long is it between high tides (or low tides)?
  • 161. A.25. A tidal bore Q.25. What do we call an abrupt rise of tidal water that moves rapidly inland from the mouth of a river estuary?