The Oceans

Essential Points1. The ocean is salty because erosion brings

dissolved elements to the sea2. The Coriolis Effect causes ocean currents

to travel curving paths3. Surface currents in the ocean are driven by

the winds4. Vertical movements in the ocean are due

to density differences

Composition of Sea WaterElementWeight %:

1%=10 gm/liter

• Cl 1.9• Na 1.05• Mg 0.135• S 0.0885• Ca 0.040• K 0.038

• Br 0.0065• C 0.0028• Sr 0.00081• B 0..00096• Si 0.00030• F 0.00013

1. The ocean is salty because erosion brings dissolved elements to the sea

Residence TimesAmount in Ocean/Rate of AdditionAl – 150 years• Very InsolubleSi – 60,000 years• Used by marine organismsCa – 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 Points1. The ocean is salty because erosion brings

dissolved elements to the sea2. The Coriolis Effect causes ocean currents

to travel curving paths3. Surface currents in the ocean are driven by

the winds4. Vertical movements in the ocean are due

to density differences

Tides

Essential Points1. Tides in the ocean are caused by both the Sun

and Moon2. Tides occur because the Sun and Moon pull

stronger on one side of the earth than the other3. There are two tidal bulges on opposite sides of

the Earth4. Solar and Lunar tidal effects can reinforce or

weaken each other5. Actual tide motions in the oceans are very

complex6. 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 Points1. Tides in the ocean are caused by both the Sun

and Moon2. Tides occur because the Sun and Moon pull

stronger on one side of the earth than the other3. There are two tidal bulges on opposite sides of

the Earth4. Solar and Lunar tidal effects can reinforce or

weaken each other5. Actual tide motions in the oceans are very

complex6. Tides are gradually slowing the earth’s rotation