1. Warm-Up: 3/4-3/5
Name 4 properties of water that you remember from biology/ES.

2. Chapter 4
Water, Waves, and Tides

3. Key Concepts
The polar nature of water accounts for many of its physical properties.
Seawater contains a number of salts, the most abundant being sodium chloride.
Salts are constantly being added to and removed from the oceans.
The exchange of energy between oceans and the atmosphere produces winds that drive ocean currents and weather patterns.

4. Key Concepts
The density of seawater is mainly determined by temperature and salinity.
Vertical mixing of seawater carries oxygen to the deep and nutrients to the surface.
Waves are the result of forces acting on the surface of the water.
The gravitational pull of the moon and the sun on the oceans produces tides.

5. Table 4-1 Physical Properties of Water

6. Nature of Water Marine organisms are 70 – 80% water by mass.
Terrestrial organisms are approximately 66% water by mass!
Physical properties of water
excellent solvent
high boiling point and freezing point
denser in its liquid form than in its solid form
supports marine organisms through buoyancy
provides a medium for chemical reactions necessary for life

7. Nature of Water Structure of a water molecule
2 H atoms bonded to 1 O atom
polar - different parts of the molecule have different electrical charges
the oxygen atom carries a slight negative charge
the hydrogen atoms carry a slight positive charge

8. Nature of Water Freezing point and boiling point
polar water molecules- Hydrogen bonds
high boiling point reflects energy needed to overcome attractive forces of hydrogen bonds
relative high freezing point (0oC) of water is a result of less energy needed to fix molecules into position to form solid

9. Figure 4-1 (b) Water Molecules.

10. Figure 4-1 (c) Water Molecules.

11. Nature of Water Water as a solvent
polar nature keeps solute’s ions in solution
water cannot dissolve non-polar molecules, e.g., oil and petroleum products

12. Figure 4-1 (d) Water Molecules.

13. (a) Polar nature of water molecule Hydrogen bond
(b) Hydrogen bonding of water molecules due to its polarity
Salt
(c) Structure of water molecules in a solid state (ice)
Stepped Art
(d) Salt crystals dissolving in water
Fig. 4-1, p. 70

14. Nature of Water Cohesion, adhesion, and capillary action
hydrogen bonds cause water molecules to be cohesive, i.e., stick together, accounting for high surface tension
adhesion - attraction of water to surfaces of objects that carry electrical charges, making them “wet”
adhesion also accounts for water’s capillary action - the ability of water to rise in narrow spaces

15. Figure 4-3 Adhesion And Capillary Action.

16. Nature of Water Specific heat (Thermal capacity) Water and light
water has a high specific heat (amount of heat energy needed to raise 1 g 1o C) due to hydrogen bonds
ocean can maintain relatively constant temperature
Water and light
much light reflected into the atmosphere
different wavelengths (colors) of light penetrate to different depths

17. Nature of Water Chemical properties of water
acids release H+ atoms in water
bases bind H ions and remove them from solution
pH scale measures acidity/alkalinity
pH of pure water is 7, considered neutral
ocean’s pH is slightly alkaline (average 8) owing to bicarbonate and carbonate ions
organisms’ internal and external pH affect life processes such as metabolism and growth

18. Increasing alkalinity
pH paper
Increasing acidity 1 2 3 4 5 6
Gastric juice
Vinegar
Urine
Rain water
Neutral
Human saliva 7
Blood
Increasing alkalinity 8 9 10 11 12 13 14
Egg white
Seawater
Great Salt Lake
Liquid soap
Oven cleaner
Stepped Art
pH scale
Fig. 4-4, p. 72

19. Salt Water Composition of seawater
most salts present in seawater are present in their ionic form
6 ions make up 99% of dissolved salts in the ocean:
sodium (Na+)
magnesium (Mg2+)
calcium (Ca2+)
potassium (K+)
chloride (Cl-)
sulfate (SO42-)
trace elements - present in concentrations of less than 1 part per million

20. Table 4-2 Major Ions In Seawater.

21. Salt Water Salinity seawater = 3.5% salt, 96.5% water
expressed as in g per kg water or parts per thousand (ppt)
salinity of surface water varies as a result of evaporation, precipitation, freezing, thawing, and freshwater runoff from land
between 10o N-10o S of equator = low salinity (due to heavy rainfall)
areas around 30o N and 30o S = high salinity (evaporation > precipitation)
from 50o = low salinity (heavy rainfall)
poles = high salinity (freezing – removes water from sea)

22. Figure 4-5 Ocean Salinity.

23. Hydrogen sulfide (H2S) Chlorine (Cl2) Sulfur Chloride (Cl–)
Precipitation
Chloride (Cl–)
Sulfate (SO42–)
Hydrogen sulfide (H2S)
Chlorine (Cl2)
Volcano
Sulfur
Sea spray
removes salts
Salts removed
when organisms are
caught for food
River
discharge
Carbonate (CO32–)
Calcium (Ca2+)
Sulfate (SO42–)
Sodium (Na+)
Magnesium (Mg2+)
Calcium (Ca2+)
Magnesium (Mg2+)
Potassium (K+)
Rock on
the seafloor
Clay particles
adsorb
Organisms
die
Bottom sediments
Precipitation
Stepped Art
Fig. 4-6, p. 75

24. Salt Water Gases in seawater gases from biological processes
oxygen is a by-product of photosynthesis
release of CO2 from respiration
oxygen-minimum zone – located just below sunlit surface waters
solubility of gases in seawater
seawater has more O and CO2 but less N than the atmosphere
relative solubility in seawater: CO2 > O > N
affected by temperature, salinity and pressure

25. Table 4-3 Gases Found in Seawater

26. Figure 4-7 (a) Gases In Seawater.

27. Salt Water role of bicarbonate as a buffer
bicarbonate formed from the solution of CO2
buffer - a substance that can maintain the pH of a solution at a relatively constant point
bicarbonate’s buffering action helps maintain the pH of seawater at a constant value, providing a stable environment for marine organisms

28. Figure 4-7 (b) Gases In Seawater.

29. Ocean Heating and Cooling
Earth’s energy budget
energy input
sun’s radiant energy heats earth’s surface
energy decreases with latitude (seasons)
energy output
Absorbed energy is released into atmosphere
Greenhouse (CO2, Mthane) gasses trap energy

30. Greater angle Less solar energy per unit area Tropic of Cancer
Right angle
More solar energy
per unit area
Equator
Tropic of Capricorn
Greater angle
Less solar energy
per unit area
Stepped Art
Fig. 4-8, p. 77

31. Figure 4-9 The Earth’s Energy Budget.

32. Winds and Currents Winds
result from horizontal air movements caused by temperature, density, etc.
as air heats, its density decreases and it rises; as it cools, density increases and it falls toward earth
wind patterns: upper air flow from the equator towards the north and south

33. Figure 4-11 North-South Air Flow.

34. Winds and Currents Winds Coriolis effect
a point rotating at the equator moves faster than a point at a higher latitude
path of air mass appears to curve relative to the earth’s surface—to the right in the Northern Hemisphere, left in the Southern

35. Figure 4-12 (a) The Coriolis Effect.

36. Figure 4-12 (b) The Coriolis Effect.

37. Winds and Currents Surface wind patterns
3 convection cells in each hemisphere:
northeast & southeast trade winds
westerlies
polar easterlies
areas of vertical air movement between wind belts
Doldrums (at equator)
horse latitudes (at 30o N & S)

38. Figure 4-12 (c) The Coriolis Effect.

39. Figure 4-13 Surface Wind Patterns.

40. Winds and Currents Ocean currents surface currents
driven mainly by trade winds (easterlies and westerlies) in each hemisphere
Coriolis effect
currents deflected to the right of the prevailing wind direction in the Northern Hemisphere, to the left in the Southern Hemisphere
deflection can be as much as 45-degree angle from wind direction
gyres—water flow in a circular pattern around the edge of an ocean basin

41. Figure 4-14 (a) Gyres.

42. Figure 4-14 (b) Gyres.

43. Winds and Currents Classification of currents
western-boundary currents: fastest, deepest currents that move warm water toward the poles in each gyre (e.g. Gulf Stream)
eastern-boundary currents: slow moving, carry cold water toward the equator
transverse currents: connect eastern- and western-boundary currents in each gyre
biological impact
western-boundary currents not productive, carry little nutrients, but increase oxygen mixed in water
eastern-boundary currents productive, nutrient-rich

44. Figure 4-15 Major Ocean Currents.

45. Winds and Currents Currents below the surface
energy transferred from winds to surface water is transferred to deeper water
deeper-water currents are deflected by the Coriolis effect, down to about 100 m
friction causes loss of energy, so each layer moves at an angle to and more slowly than the layer above, creating an Ekman spiral
Ekman transport—net movement of water to the 100-m depth

46. Figure 4-16 Ekman Spiral.

47. Ocean Layers and Ocean Mixing
Density—the mass of a substance in a given volume, usually measured in g/cm3
density of pure water = 1 g/cm3
density of salt water = g/cm3
Density increases when salinity increases
Density increases when temperature decreases

48. Figure 4-17 Effect OF Temperature And Salinity On The Density Of Seawater.

49. Ocean Layers and Ocean Mixing
Characteristics of ocean layers
depth m (330 feet): warmed by solar radiation, well mixed
100-1,000 m: temperature decreases
thermocline – zone of rapid temperature change
halocline: salinity increases 0-1,000 m
pycnocline: 100-1,000 m, where changes in temperature and salinity create rapid increases in density
seasonal thermoclines

50. Figure 4-18 (a) Changes In Temperature, Salinity, And Density Of Seawater With Depth.

51. Figure 4-18 (b) Changes In Temperature, Salinity, And Density Of Seawater With Depth.

52. Figure 4-18 (c) Changes In Temperature, Salinity, And Density Of Seawater With Depth.

53. Figure 4-19 Seasonal Changes And Vertical Mixing.

54. Water column stabilizes
Fall
Air temperature
cools
Surface water
cools, displaces
less dense
water
Colder denser
water
Summer
Warm surface water
Thermocline
Isopycnal
Wind
Winter
Water column unstable
Spring
Air temperature warms
Surface water warms
Colder denser
water
Thermocline
Water column stable
Storms drive surface
water deeper
Water column stabilizes
Stepped Art
Fig. 4-19, p. 86

55. Ocean Layers and Ocean Mixing
Horizontal mixing
higher density causes water at 30o N to form a curved layer that sinks below less-dense equatorial surface water and then rises to rejoin the surface at 30o S
even denser water curves from 60o N to 60o S below other surface waters
winter temperatures and increased salinity owing to freezing result in very dense water at the poles, which sinks toward the ocean floor

56. Ocean Layers and Ocean Mixing
Vertical mixing
vertical overturn results when denser water at the top of the water column sinks while less-dense water rises
isopycnal—stable water column that has the same density from top to bottom
vertical mixing allows water exchange between surface and deep waters
nutrient-rich bottom water is exchanged for oxygen-rich surface water

57. Figure 4-20 Vertical Overturn.

58. Ocean Layers and Ocean Mixing
Upwelling and downwelling
equatorial upwelling
water from currents on either side of the equator is deflected toward the poles, pulling surface water away to be replaced by deeper, nutrient-rich water
coastal upwelling
Ekman transport moves water offshore, to be replaced by deeper, nutrient-rich water
coastal downwelling
coastal winds force oxygen-rich surface waters downward and along the continental shelf

59. Figure 4-21 Upwelling And Downwelling Zones.

60. Ocean Layers and Ocean Mixing
Deepwater circulation
differences in density, not wind energy, cause water movement in deep oceans
densest water of all is Antarctic Bottom Water, mostly formed in winter in the Weddell Sea
dense Antarctic water sinks to the bottom and moves slowly toward the Arctic
some North Atlantic Deep Water moves into the North Atlantic via a channel east of Greenland
high-salinity Mediterranean Deep Water flows through the Strait of Gibraltar into the Atlantic Ocean

61. Waves
Wave formation
wave: a flow of energy or motion, not a flow of water
generating force: a force that disturbs the water’s surface, e.g., wind, geological events, falling objects, ships
restoring force: the force that causes the water to return to the undisturbed level
surface tension for capillary waves
gravity for gravity waves

62. Figure 4-22 Characteristics Of Waves.

63. Waves
Types of waves
Progressive (forced) waves are generated by wind and restored by gravity, progress in a particular direction
forced waves are formed by storms, which determine their size and speed
free waves, no longer affected by the generating force, move at speeds determined by the wave’s length and period
swells are long-period, uniform free waves which carry considerable energy and can travel for thousands of km

64. Waves Types of Waves (con’t) deepwater and shallow-water waves
deepwater waves—waves that occur in water that is deeper than ½ of a wave’s wavelength
breakers
deepwater waves become shallow-water waves when they move into shallow water
surf zone—area along a coast where waves slow down, become steeper, break, and disappear
breakers form when the wave’s bottom slows but its crest continues at a faster speed

65. Figure 4-23 Breakers.

66. Waves Types of Waves (con’t) Tsunamis (large seismic sea waves)
seismic sea waves are formed by earthquakes
tsunamis have long wavelengths, long periods and low height
compression of the wave’s energy into a smaller volume upon approaching a coast pr island causes a dramatic increase in height

67. Figure 4-24 Tsunami.

68. Tides
Tides: periodic changes in water level occurring along coastlines
Why tides occur
tides result from the gravitational pull of the moon and the sun
though smaller, the moon is closer to earth, so its gravitational pull is greater
water moves toward the moon, forming a bulge at the point directly under it
the centrifugal force opposite the moon forms another bulge
areas of low water form between bulges

69. Figure 4-25 Tides.

70. Tides Spring and neap tides
during spring tides, the times of highest and lowest tides, the earth, moon and sun are in a line and act together creating highest and lowest tides
when the sun and moon are at right angles, the sun’s pull offsets the moon’s, resulting in neap tides, which have the smallest change between high and low tide

71. Figure 4-26 Spring And Neap Tides.

72. Tides
Tidal range
diurnal tide: one high tide and one low tide each day
semidiurnal tide: two high tides and two low tides each day (most common)
mixed semidiurnal tide: high and low tides are at different levels
flood tides are rising; ebb tides are falling
tidal currents are associated with tidal cycle
slack water occurs during the change of tides

73. Figure 4-27 (a, b & c) Tidal Patterns.

74. Figure 4-27 (d) Tidal Patterns.