3. The nature of water
Atom: The basic unit of
matter
The smallest unit into
which an element can be
divided and still retain
its properties
4. The nature of water
Element: A substance composed entirely of one type of
atom
Molecule: Larger particle composed of two or more
atoms chemically bonded together
5. The nature of water
Hydrogen bonds: Weak
bonds between polar
molecules
polar molecule: a
molecule with uneven
distribution of charge
The reason for water’s
unique properties
6.
7. States of Water
Liquid, Gas/Vapor, and Solid/Crystalline
Water is the only substance that naturally occurs in all
three forms
8. States of Water
Liquid -> Gas/Vapor
Evaporation: The breaking of hydrogen bonds allows
water to change from the liquid phase into the gaseous
phase
9. States of Water
Gas/Vapor -> Liquid
Condensation: The formation of hydrogen bonds
allows water molecules to come together and change
from a gaseous phase to a liquid phase
10. States of Water
Solid -> Gas/Vapor
Sublimation: The
direct change in
phase from a solid to
a gas without a
change in phase to a
liquid in between
12. States of Water
Density = Mass/Volume
Water is the only known substance that is less dense as
a solid than it is as a liquid
13.
14. Heat and Water
Latent heat of melting:
The amount of heat
required to melt a
substance
highest among
common substances
due to hydrogen
bonding
15. Heat and Water
Heat capacity: The amount of heat needed to raise a
substance’s temperature by a given amount
reflects how much heat a substance can store
water can absorb large amounts of heat without altering
much
why water is used a common coolant
ex. car engines
16. Heat and Water
Latent heat of evaporation: the amount of heat energy
that is needed to evaporate a substance
water has a high latent heat of evaporation
also due to hydrogen bonding
Only fastest moving bonds are broken, allowing those
molecules with more energy to evaporate
lower energy molecules are left behind
17. Heat and Water
Evaporative cooling: the lower
speed and therefore lower
temperature of molecules
remaining in the liquid phase
after evaporation of the fastest
molecules
how evaporating sweat cools our
skin
18.
19. Water as a Solvent
Seawater is a solution: A mixture consisting of two
parts a solvent and a solute which is evenly dissolved
throughout the mixture
The solute is the substance being dissolved
The solvent is the substance that causes the dissolving
20. Water as a Solvent
Often considered
the “Universal
solvent”
can dissolve more
things than any
other natural
substance
21. Water as a Solvent
Salts: Substances made up of particles with opposite
charges
Ions: Electrically charged particles that result from the
loss or gain of an electron
ex. NaCl -> Na+ and Cl-
22. Water as a Solvent
Dissociation: The separation of two oppositely charged
particles in a substance into their individual ions
ex. NaCl -> Na+ and Cl-
23.
24. Seawater
The characteristics of
seawater are due to two
things:
1. the nature of pure water
2. the materials dissolved in
the water
25. Seawater
Some of the material
dissolved in seawater is
the result of weathering
of surrounding rocks
Weathering: the
physical or chemical
breakdown of rocks
26. Seawater
Salinity: The total amount of
salt dissolved in seawater
Salinity is usually defined as the
amount of salt in grams that
remains when 1,000 grams of
seawater are evaporated
ex. 35 g remains, 35 parts per
1000 or 35 ppt
this is the average salinity of the
ocean
27. Seawater
Today electronic equipment is used to measure salinity
The conductivity of seawater is a good indicator of its
salinity - ions are charged
28. Seawater
Organisms are affected by the concentration of salts
and the types of salt found in particular seawater
ex. Cl usually makes up 55.03% no matter what else is
present
This idea is called the rule of constant proportions
relative amounts of the various ions in seawater are
always the same
29. Seawater
Water is primarily
removed by evaporation
and less by freezing
when seawater freezes,
the ions are excluded
from the ice
ice is almost pure water
Water is added by
precipitation
30.
31. Salinity, Temperature, Density
Temperature and salinity effect water’s density
it gets denser as it gets saltier, colder or both
Temperature in the open ocean varies from -2°C 30°C
(28-86°F)
Temperature varies more than salinity
32. Salinity, Temperature, Density
Sampling Bottles - measure temperature and salinity
ex. Niskin bottles
set up a rack with multiple bottles attached at different
locations, measure many depths at once
35. Salinity, Temperature, Density
Profile: a plot that shows temperature, salinity, or any
other characteristic of seawater at various depths in a
water column
36. Salinity, Temperature, Density
Today electronic sensors are
more commonly:
CTDs: Conductivity-
Temperature-Depth meters
XBTs: Expendable
Bathythermographs
disposable, temperature
measures
Problem: only measure one
location at a time
37.
38. Pressure
Organisms on land, at sea level, are under 1 atm of
pressure, or the pressure of the atmosphere above
them
39. Pressure
Organisms in the water are under pressure from the
atmosphere and the water above them
Every 10 ft of depth, 1 atm of pressure is added
Problem for fish as well
gas bladder
43. Dissolved Gases
3 most important for living organisms:
1. Oxygen (O2)
2. Carbon Dioxide (CO2)
3. Nitrogen (N2)
44. Dissolved Gases
Gas exchange: the movement of gases between the
atmosphere and the ocean
Gases dissolve better in cold water
Oxygen is not very soluble
The amount of oxygen in the water is strongly affected
by organisms through the processes of photosynthesis
and respiration
47. Dissolved Gases
CO2 is more easily dissolved, because it chemically
reacts with water
makes up more than 80% of the dissolved gas in the
ocean
only makes up 0.04% of air
Makes the ocean critical to understanding the effects
of human activities on the earth’s climate
48.
49. Transparency
Water is transparent
allows sunlight to enter
allows for photosynthesis to occur and life to continue
50. Transparency
Not all colors penetrate seawater equally
Clear ocean water is most transparent to blue light
Other colors are absorbed more than blue, so as the
depth increases only blue light can get through
51. Transparency
The transparency of
water is greatly affected
by the material
suspended in the water
and the gases dissolved
in the water
52.
53. The Coriolis Effect
The Earth is round, therefore anything that moves
over the surface tends to turn at least a little and
does not move directly in a straight line.
This bending is called the Coriolis Effect
named after Gustave-Gaspard Coriolis who discovered it
in 1835
54. The Coriolis Effect
In the Northern Hemisphere always turns to the right
In the Southern Hemisphere always turns to the left
55.
56. Wind Patterns
winds in our atmosphere are driven by heat energy
from the sun
As solar energy heats the Equator the air there
becomes less dense and rises.
Surrounding air gets sucked in to replace the risen air,
creating wind
The winds are bent due to the Coriolis effect
57. Wind Patterns
These winds near
the Equator are
called trade
winds
approach the
Equator at 45
angles
least variable of
the winds
58. Wind Patterns
Other winds
tend to be
more variable
Middle
latitudes -
westerlies
High latitudes
- polar
easterlies
61. Surface Currents
Due to the Coriolis effect,
when the wind moves off,
the water is pushed off at a
45 degree angle
The top layer of water then
pushes on the next layer and
again the Coriolis effect
comes into play
The next layer moves more
slowly and slightly towards
the right of the top layer
62. Surface Currents
Each successive layer in the water column follows this
pattern
Forms a pattern called the Ekman spiral after the
Swedish oceanographer who discovered it
ekman spiral
63. Surface Currents
At a depth of a
few 100 meters
the effect of the
wind is not felt
at all
The upper part
of the water
column that is
affected by the
wind is called
the Ekman layer
64. Surface Currents
Taken as a whole the
Ekman layer moves at 90
degrees from the wind
direction in a process
known as Ekman
transport
Equatorial currents move
parallel to the equator
65. Surface Currents
Under the influence of the Coriolis effect the wind-
driven surface currents combine into huge, more or
less circular systems called gyres
particularly good at carrying heat due to water’s high
heat capacity
67. Surface Currents
Large scale fluctuations in current patterns such as El
Nino can dramatically affect weather around the world
68.
69. Three-Layered Ocean
Surface layer: 100-200m
thick
mixed by wind, waves and
current
“mixed layer”
heated by the sun
The warmer water floats in a
shallow “lens” on top and
there is a sharp transition to
the cooler water below
72. Three Layered Ocean
Thermocline: sudden changes
in temperature over small
depth intervals
When the weather cools, the
thermocline breaks down by
winds, waves and currents
73. Three Layered Ocean
Intermediate Layer: below the surface level
1,000-1,500 m in depth (200 – 1,200/1,700 m from the
surface)
main thermocline: a zone of transition between warm
surface water and the cold water below
rarely breaks down
feature of the open ocean
77. Stability and Overturn
How stable the water column is
depends on the density difference
between the layers
A more stable water column has
greater differences in density and
requires more energy to mix the
layers
78. Stability and Overturn
Sometimes the columns become unstable, meaning
the surface water is more dense than the water below
the surface water sinks causing downwelling
this water displaces and mixes with deeper water
79. Stability and Overturn
Process is known as overturn
Scientists identify overturn by looking at straight line
profiles
When difference is only slight and mixing occurs,
important for the productivity of temperate and polar
waters
80. Stability and Overturn
When large amounts of downwelling occurs, the
salinity of that area is changed
once it has sunk, temperature and salinity do not
change
81. Stability and Overturn
From this point on the volume of water or water mass
has a “fingerprint” - a characteristic combination of
temperature and salinity
This is called Thermohaline circulation
82.
83. Great Ocean Conveyor
Overturn rarely reaches the ocean bottom, only in a
few locations - Atlantic Ocean, south of Greenland
and just north of Antarctica
84. Great Ocean Conveyor
After sinking the water
spreads through the
Atlantic and to other
ocean basins
Water eventually rises
back to the surface
flows back to the
Atlantic where the cycle
begins again
This is called the Great
Ocean Conveyor
85. Great Ocean Conveyor
mixes the oceans
about every 4,000
years
critical to regulating
the earth’s climate
brings dissolved
oxygen to the deep sea
86. Great Ocean Conveyor
It is thought that alterations in the conveyor have
produced rapid climate changes, even ice ages, in the
past
87.
88. Waves
Wind causes waves
Wave: the undulation that forms as a disturbance
moves along the surface of the water
89. Waves
Crest: The highest
part of the wave
under a crest the
water moves up
and forward
Trough: The lowest
part of the wave
under a trough the
water moves down
and back
90. Waves
Basically, water particles don’t go anywhere when a
wave goes past, they just move in a circle
Waves carry energy, but not water
91. Waves
The size of a wave is
usually expressed as
the (amplitude)
wave height: the
vertical distance
from trough to crest
92. Waves
Wavelength: the horizontal distance between crests
Period: the time the wave takes to move past a given
point
93. Waves
The faster and longer the wind blows, the larger the
wave
The size of the wave also depends on fetch: the span of
open water over which the wind blows
94. Waves
Seas: While the wind is blowing it pushes the wave
crests up into sharp peaks and “stretches out” the
troughs, these waves are called seas
95. Waves
Waves move away from where they are generated
slightly faster than the speed of the wind
Once away from the wind they settle into swells
smoothly rounded crests and troughs
96. Waves
As waves approach the shoreline and reach shallow
water, they begin to “feel” the bottom of the ocean
The bottom forces the water particles to move in
elongated ellipses instead of circles, which slows the
wave
As the waves behind catch up the waves get closer
together, giving a shorter wavelength
98. Waves
As the waves behind
catch up the waves get
closer together, giving a
shorter wavelength
These waves pile up -
higher and steeper
Eventually topple over
or “break” - creating
surf
99. Waves
When two crests of two waves collide, they add
together producing a higher wave
This is called Wave Reinforcement
101. Waves
When a crest and a trough collide, they cancel each
other out
This is called wave cancellation
102.
103. Tides
The dominant force on near
shore sea life.
They alternately expose and
submerge organisms on the
shore, drive the circulation
of bays and estuaries,
trigger spawning and
influence the lives of marine
organisms in countless
other ways
104. Tides
The tides are caused by the gravitational pull of the
moon and sun/and the rotations of the sun, moon and
earth
105. Tides
The earth and moon both rotate around a common
point, their combined center of mass
This rotation produces a centrifugal force
106. Tides
Centrifugal force: The force that
tends to push a body away from the
center of rotation
force that pushes you outward on a
merry-go-round
balances the gravitational
attraction between the earth and
moon
without it the two would either fly
away from each other or crash
together
107. Tides
centrifugal force and the moon’s gravity are not in
perfect balance everywhere along the earth’s surface
the side of the earth nearest the moon, the moon’s
gravity is stronger
pulls water towards the moon
side away from the moon
centrifugal force is stronger
pushes water away from the moon
109. Tides
Earth is spinning on its axis
any given point on the earth’s surface will be the first
under a bulge then away from a bulge
high tide occurs when that point is under the bulge
110. Tides
Earth takes 24 hours to complete a rotation
Moon advances a little on its orbit every day
full tidal cycle takes 24 hours and 50 minutes
111. Tides
Tidal range: difference in water level between
successive high and low tides
112. Tides
Sun produces tidal bulges in the same way as the moon
Sun is larger than the moon but 400 times further
away
effect of the sun on the tides is half that of the moon
113. Tides
When the sun and the moon are in line with each
other, full moons and new moons the effects are added
together
tidal range becomes large
114. Tides
spring tides: the
tides with a large
tidal wave, occur
around the time of
new or full moons
occur once every
two weeks
115. Tides
When the sun and moon
are at right angles their
effects partially cancel
each other
Neap Tides: tides with a
small tidal range
Occurs when the moon is
in quarter (first or third)
116.
117. Tides
Tides in the real world
behave slightly
differently
They vary based on:
1. location
2. shape of the basin
3. depth of the basin
118. Tides
There are three types of tidal occurrences:
1. semi-diurnal
2. mixed semi-diurnal
3. diurnal
119. Tides
Semidiurnal tides: A tidal pattern with two high and
two low tides each day
East coast of N. America most of Europe and Africa
120. Tides
Mixed Semidiurnal tides: A tidal pattern with two
successive high tides of different heights each day
West coast of N. America and Canada
121. Tides
Diurnal tides: One high and one low tide every day
uncommon
coast of Antarctica and parts of the Gulf of Mexico
Caribbean and Pacific
122. Tides
Tide Tables: A table that gives the predicted time and
height of tides for particular points along a coast
give values for one particular place
124. Tides
Effected by channels, reefs, basins and other local
features
Weather patterns also effect tides
strong winds, can pile water up on shore
