Most materials expand when heated
and contract when cooled.
~ contracts until
cooled to 39.2° F (4° C)
~ expands rapidly as it
freezes at 32° F (0° C)
~ increases in volume
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.
The vast world ocean:
• Enormous heat-controlling thermostat
• Absorbs and loses heat more slowly
• Currents transfer heat to other areas
~ cooler in
~ warmer in
Near coasts or Great Lakes, people
know that near the water it is:
Water is not compressible except in the
extreme pressure of depth or laboratory.
It cannot be made smaller in cubic volume.
Water can “turn over” allowing warmer
and colder waters to exchange depths
Water can also evaporate from the
surface aided by wind and wave action.
Seawater’s ability to
transmit light is
important to life
in the oceans.
Chemically, seawater is very pure, more
than 95% water (hydrogen and oxygen).
The remaining 5% contains about 80
elements in solution or suspension.
5% Other Elements
95% Hydrogen and Oxygen
The 5% not Hydrogen (H) or Oxygen (O)
is mostly Sodium (NA) or Chloride (CL),
Some parts of the Red Sea in the
summer have salinities as high as 41.
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.
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.
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
(a.k.a. Water Cycle)
Plants on land
also add to the
amount of water
the air in a
Today, only magnesium (Mg) and
bromine (Br) are taken commercially
A full one-third lighter than aluminum,
magnesium is used to manufacture
lightweight alloys for airplanes and
Bromine is used in the oil/gas drilling
industry and, in combination with other
elements, to manufacture flame
Research is constantly under way to
develop profitable ways to extract
dissolved minerals from the sea.
This is the area of oceanography and
metallurgy that will undoubtedly expand
as continental mineral resources are
Upper ocean water temperature varies
from about 32° F in the polar regions
to a high of 85° F in the Persian Gulf.
(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
bathy + thermo + graph
depth temperature record
Bathythermographs, commonly called
BTs, are instruments used to check
water temperatures at various depths.
An instrument that makes a record
of the temperature at various depths
in the ocean
Most Navy combatants have
expendable BTs (XBTs) to
Nansen bottles are metal cylinders with
automatic closing valves on each end
that shut to collect water samples.
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
When valves close,
a mercury column
outside the bottle
test for salinity,
In shallow places, ocean water appears
light green, while in deeper water it
seems to be blue, gray, or dark green.
The Red Sea is so
named because of
in the water.
The Yellow Sea is so named because
of the yellow silt carried into it by
rivers in northern China.
Sunlight consists of a range (spectrum)
of different wavelengths of energy.
Radiation with wavelengths
longer than visible light but
shorter than radio waves
Radiation with wavelengths
shorter than visible light but
longer than X rays
Using a prism will display the visible
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.
~ 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
3 to 330
260 to 655
Life in the sea is
No effective plant
No plants grow
and animal life
Depth (in feet)
Ocean Light Environments
Waves are caused by any energy
source that disturbs the water
to a water surface
will cause ripples.
Tsunami waves (huge ripples) can
travel thousands of miles across an
Wind is the most common cause of
ordinary waves. Sailors often call
wind-driven waves “sea” or the state
of the sea.
may indicate an approaching storm
are quite common before hurricanes
A long wave on water that
moves continuously without
• Wind speed
+ Duration of wind
+ Length of fetch
= determines wave height
The distance over which a wind
The distance traveled by waves
with no obstruction
People who have had the misfortune of having
a beach cottage undermined or washed away
during gales and hurricanes know what this
Waves and currents
produced by waves
cause most shoreline
The U.S. coastline is
eroding about 1 foot
However, in other places like the
Mississippi River Delta, waves and
currents build shoreline with
Carried by wave action, small fragments
of rock and sand scour away beaches
and wear down shoreline.
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.
Engineers must account for local wave
refraction to take advantage of it when
designing protective structures.
Most common harbor protection is a
breakwater (line of big rocks) sometimes
with steel-reinforced concrete.
The protective structure of stone or
concrete; extends from shore into
the water to prevent a beach from
A barrier that protects a harbor or
shore from the full impact of waves
Another common structure is a groin,
walls of stone or wooden pilings built
at right angles to a shoreline.
Cape May, New Jersey
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.
Rip currents are strong, seaward
moving currents. They occur when
opposing longshore currents meet.
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 and undertow are not the
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.
~ rarely over 100 feet wide
~ swim parallel to the shore
~ don’t panic
Ocean currents have profound effects
on people, weather, and food cycles.
Studying ocean currents can be complex.
Earth’s atmosphere (winds) and
oceans (currents) are linked.
Gaspard de Coriolis
The Earth’s rotation creates an invisible
force called the Coriolis effect.
Objects deflect to
the left in the
The apparent deflection of moving
objects relative to an observer on the earth
Objects deflect to
the right in the
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
Two important factors affect global
movement of wind and water:
• Wind acting on water surface
• Boundary effects of the continents
The water level of the Sargasso Sea
is 3 feet higher than along the west
coast of the Atlantic Basin.
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.
In the Northern Hemisphere, prevailing
winds are from the northeast from 0° to
In the Southern Hemisphere, prevailing
winds are from the southeast from 0° to 30°.
Keep in mind:
Winds ~ described by coming from.
Currents ~ described by flowing to.
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
A NE current and a SW wind are headed
in the same direction.
The most important current affecting
the U.S. and Atlantic seaboard
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
An oval 2,000 miles E-W by 1,000 miles
N-S, Sargasso Sea forms an oceanic
desert with specially adapted plant life.
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.
The currents of the Gulf Stream and
North Atlantic Drift warm the regional
climate more than any other area at
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
Hurricanes often track the Gulf Stream
into the Caribbean and Gulf of Mexico
or up the East Coast of U.S.
Ocean South Pacific
Typhoons are the Pacific equivalent
of Atlantic hurricanes, with the
Western Pacific averaging 20 per
Similar to Atlantic hurricanes, Pacific
typhoons follow the warm current
running near land.
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.
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.
In 1955, Dr. John
a floating under-
water device (a
Swallow buoy) to
aid tracking of
deep current flow.
Dr. John Swallow
Surface current and countercurrent
vertical mixing bring rich nutrients
upwards drawing large number of fish.
Distinct layers influence underwater
sound transmission, important in
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.
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
The pull of gravity is very small for small
objects, but enormous for a planet, moon
Gravity alignment and centrifugal force interact
to create variable bulges in the Earth’s oceans.
The Sun causes
tides also, but
with only about
two-fifths of the
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.
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
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
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
The ebb of a tide is the fall of the
tide, that is, the moving of the tide
away from the shore.
Receding or outgoing tide
The period between high water
and the succeeding low water
The flood of the tide is the rise of the
tide, or the flowing of the tide toward
the shore to its highest point.
Incoming or rising tide
The period between low water
and the succeeding high water
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.
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.
Tidal flows are critical for ship personnel.
~ slack or tension in mooring lines
~ harbor and channel navigation
~ boat runs and schedules
Tides in mid-ocean are measurable
only with scientific instruments.
(12 feet ±)
(50 feet +)
Tidal ranges vary
from location to
location. In some
in high northern
Spring tide at the
Bay of Fundy often
exceeds 50 feet.
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.
The Inchon, Korea harbor encloses
its piers with graving basins or docks
that hold in the 40-foot tidal waters.
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).
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.
For centuries, the Dutch have reclaimed
land from the sea with dikes and pumps.
The largest project was enclosing
the Zuyder Zee.
• 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
Q.1. TRUE or FALSE. Pure water is
composed of two (2) atoms of
oxygen and one (1) atom of
Q.2. TRUE or FALSE. Plants and
animals can live indefinitely
A.3. Solid, Liquid, and gas
Q.3. Name the three forms in which
water can exist.
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
A.5. Sodium, hydrogen, oxygen, and
Q.5. What are the major components
Q.6. TRUE or FALSE. Sound travels
faster in water than in air.
Q.7. What is the term used to
describe the dissolved salts in
Q.8. TRUE or FALSE. The
designed to measure the salinity
of the water more accurately.
A.9. Nansen bottle
Q.9. What is the name of the
instrument that captures salt
water at depth?
A.10. The Dead Sea between Israel
Q.10. What body of water has the
highest salt content of any on
A.11. The passage of water through
a plant from the roots through
the vascular system to the
Q.11. What is transpiration?
A.12. Wind speed, duration of the
wind, and length of the fetch
Q.12. What three (3) principal factors
does wave height depend?
A.13. The slope or gradient of the
Q.13. As a wave moves ashore, what
determines the kind of breaker
it will become?
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
A.15. A swimmer should swim
parallel to the shore (across
the current) since a rip current
is rarely more than 100 feet
Q.15. If caught in a rip current, what
should a swimmer do?
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
Q.16. What is the Coriolis Effect?
Q.17. What do we call the circular
system of currents that rotate
clockwise in the Northern
counterclockwise in the
A.18. The Gulf Stream
Q.18. What is the most important
current affecting the U.S. East
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
Q.19. What did Townsend Cromwell
discover in 1952?
A.20. The Moon
Q.20. What is the main cause of the
rise and fell (ebb and flow) of
the ocean tides?
A.21. Spring tides
Q.21. What do we call tides when
they are at their highest and
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
Q.22. What phase(s) is the Moon in
during the spring tides?
A.23. Neap tides
Q.23. What do we call tides whose
range is less than average?
A.24. 12 hours and 25 minutes
Q.24. Approximately how long is it
between high tides (or low
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?