The Oceans
Essential Points
1. The ocean is salty because erosion brings
dissolved elements to the sea
2. The Coriolis Effect causes ocean currents
to travel curving paths
3. Surface currents in the ocean are driven
by the winds
4. Vertical movements in the ocean are due
to density differences
Composition of Sea Water
Element
Weight %:
1%=10
gm/liter
•
•
•
•
•
•
Cl
Na
Mg
S
Ca
K
1.9
1.05
0.135
0.0885
0.040
0.038
•
•
•
•
•
•
Br
C
Sr
B
Si
F
0.0065
0.0028
0.00081
0..00096
0.00030
0.00013
1. The ocean is salty because erosion brings dissolved elements to the sea
Residence Times
Amount in Ocean/Rate of Addition
Al – 150 years
• Very Insoluble
Si – 60,000 years
• Used by marine organisms
Ca – 8 million years
• Used by marine organisms
1. The ocean is salty because erosion brings dissolved elements to the sea
Why the Ocean is Salty
• Ca is 2.5 times as abundant in river water
as Na
• Ca is used by marine organisms
• Na and Cl have residence times > 100
million years
1. The ocean is salty because erosion brings dissolved elements to the sea
Rotation Effects
2. The Coriolis Effect causes ocean currents to travel curving paths
The Coriolis Effect
• Due to moving on a
rotating earth
• Things on equator are
moving faster than
points near poles
• Affects:
– Winds
– Ocean Currents
– Tides
2. The Coriolis Effect causes ocean currents to travel curving paths
The Coriolis Effect
• Things moving
toward the equator
are deflected west
• Things moving
poleward are
deflected east
• Deflected to Right in
Northern Hemisphere
• Deflected to left in
Southern Hemisphere
2. The Coriolis Effect causes ocean currents to travel curving paths
Not a
Manifestation of
the Coriolis
Effect!
• Too small scale
for the Coriolis
Effect to be
significant
Ocean Currents
3. Surface currents in the ocean are driven by the winds
Tracking Ocean Currents
The Global Heat Conveyor
4. Vertical movements in the ocean are due to density differences
Essential Points
1. The ocean is salty because erosion brings
dissolved elements to the sea
2. The Coriolis Effect causes ocean currents
to travel curving paths
3. Surface currents in the ocean are driven
by the winds
4. Vertical movements in the ocean are due
to density differences
Tides
Essential Points
1. Tides in the ocean are caused by both the Sun
and Moon
2. Tides occur because the Sun and Moon pull
stronger on one side of the earth than the other
3. There are two tidal bulges on opposite sides of
the Earth
4. Solar and Lunar tidal effects can reinforce or
weaken each other
5. Actual tide motions in the oceans are very
complex
6. Tides are gradually slowing the earth’s rotation
There
are Two
Tidal
Bulges
3. There are two tidal bulges on opposite sides of the Earth
Both Moon and Sun Cause Tides
4. Solar and Lunar tidal effects can reinforce or weaken each other
Tides and the Boston Tea Party,
December 16, 1773
•
•
•
•
Near Earth's perihelion: strong solar tides
Near lunar perigee: strong lunar tides
Full moon on December 13: spring tide
Overall effect: unusually large tidal range
4. Solar and Lunar tidal effects can reinforce or weaken each other
The Boston Tea Party, December 16,
1773
4. Solar and Lunar tidal effects can reinforce or weaken each other
Tides and the Battle of Tarawa,
November 20, 1943
•
•
•
•
Near Earth's perihelion: strong solar tides
Near lunar apogee: weak lunar tides
Near last-quarter moon: neap tide
Overall effect: unusually small tidal range
4. Solar and Lunar tidal effects can reinforce or weaken each other
Location of Tarawa
4. Solar and Lunar tidal effects can reinforce or weaken each other
The Attack on Tarawa
4. Solar and Lunar tidal effects can reinforce or weaken each other
Tarawa: What the Planners Wanted
4. Solar and Lunar tidal effects can reinforce or weaken each other
What Actually Happened
1027 Marines killed, 2292 wounded
4. Solar and Lunar tidal effects can reinforce or weaken each other
Tides and the
Real Oceans
5. Actual tide motions in the oceans are very complex
The Gulf of St. Lawrence
5. Actual tide motions in the oceans are very complex
The Gulf of St. Lawrence
5. Actual tide motions in the oceans are very complex
How Tides Move in the Oceans
5. Actual tide motions in the oceans are very complex
Tides on the Real Earth
5. Actual tide motions in the oceans are very complex
Diurnal, Mixed and Semidiurnal Tides
5. Actual tide motions in the oceans are very complex
Global Tide Types
5. Actual tide motions in the oceans are very complex
Global Tide Heights
5. Actual tide motions in the oceans are very complex
Tides in Confined Spaces
5. Actual tide motions in the oceans are very complex
Tides in Confined Spaces
5. Actual tide motions in the oceans are very complex
Tides
Affect
Earth's
Rotation
6. Tides are gradually slowing the earth’s rotation
Essential Points
1. Tides in the ocean are caused by both the Sun
and Moon
2. Tides occur because the Sun and Moon pull
stronger on one side of the earth than the other
3. There are two tidal bulges on opposite sides of
the Earth
4. Solar and Lunar tidal effects can reinforce or
weaken each other
5. Actual tide motions in the oceans are very
complex
6. Tides are gradually slowing the earth’s rotation