Oceanography 1

Origins of Ocean, History of Oceanography,

How did our solar system form?

A solar nebula condensed from a past exploded star

Hydrogen concentrated and condensed to form our sun

Nebular rotates as it condenses

Organized over time to form planets

How do we know how our solar system was founded is true?

We can see it happen elsewhere in the galaxy!

What was Earth like in the early days? How was the core and mantle and crust formed?

Earth was molten (collision and other energy generated heat)

Heavier molten iron sank to the core, lighter material rose to become the crust

Outside crust comes from ejected material (volcanoes and earthquakes, etc.)

Is the inner or outer core solid?

Inner core is solid

Outer core is liquid

Which is denser, oceanic crust or continental crust?

Oceanic is denser, but continental is thicker

Where did water even come from? Two different theories and explain how much water molecules each provide.

Well, it is first off a theory that Earth eventually cooled enough to support liquid water…

1. Volcanoes eject hydrated minerals, and the heat from volcanoes takes water out of the minerals. Currently, volcanoes emit:
   - 50-60% H2O
   - 24% CO2
   - 13% SO2

2. Comets and asteroids are made of ice and rock! They hit Earth’s surface and brought in alien water OOOooooOOO

What does it mean that Earth is a Goldilocks Zone?

Not too far from sun that water doesn’t freezes, not too close that it’ll condense.

What happened to the oceans on Mars?

There used to be water, but then Mars lost its magnetic field (which Earth has thanks to the moving iron in Earth’s core)

Most of the atmosphere escaped to space and its oceans are frozen as a polar ice cap.

Why are all planets rotating around the sun in the same direction?

They all formed from a rotating solar nebula

Who were the first Oceanographers?

Australia’s Aborigines!

• came to australia 50,000 years ago

• 300 miles of open ocean

How did the Aborigines learn how to cross 300 miles of open ocean?

Sea level was lower so it was actually more like 100 miles to hit some islands that they could use to hop to Australia.

How do we know the Aborigines were purposefully navigating the ocean, classifying them as oceanographers?

They had landing points!

What do the sticks represent on a Polynesian Stick Map? What about the curved palm fronds? Stones/shells?

Sticks = currents and wave directions

Palm fronds = the way that waves bend around an island

Stones/shells = islands

How did Eratosthenes calculate the circumference of the earth?

He measured how differently the Sun cast shadows in two locations (Syrene at equator) (Alexandria up North), determined what fraction of a circle separated them, and multiplied the distance between them to estimate the size of Earth.

What is latitude. Longtitude. And degrees possible for both.

Latitude: parallel (horizontal) ; 0 - 90 degrees (reference equator)

Longtitude: Vertical lines ; 0 - 180 degrees E or W (reference prime meridian)

How do you calculate latitude?

Sextant and a North Star!

• measure the angle between the horizon with North Star (or southern cross or sun) with a sextant.

How do you calculate Longitude?

With a chronometer (clock).

Need a clock because Earth is constantly moving so you need to tell the time of the Prime Meridian (Greenwhich) and calculate distance from there and here.

Every 1 hour is a 15 degrees.

What did James Cook do? 4 things

1. Outlined Pacific Ocean

2. Discovered new land and islands for Europeans

3. Made first accurate maps of oceans using a chronometer (longitude)

4. Measured surface ocean conditions

exploitative journeys

What was the first oceanographic journey purely for science?

HMS Beagle and Charles Darwin

• Galapagos

• Evolution

What was the first modern deep-ocean expedition and what did they do?

HMS CHALLENGER (Thomas and Murray)

• measured conditions of deep oceans

• measured depth in several hundred locations with deep ocean sounding

• found life at all depths

What did the Meteor Expedition do?

Echo Sounding and mapped bottom of the oceans!

Calculates depth using travel time of sound waves

How do satellites help Bathymetry?

Generally, areas in the ocean that are deeper pull some water down with it cause of gravity. Similarly, taller heights push water upwards. Cause of water’s polar properties.

Satellites can stare at 1 spot for a long period of time and tell.

Difference between Arctic (N) and Antarctica (S)

Arctic:

• less cold overall

• polar bears (land animals)

• More diverse ecology

• Territory belongs to different countries

Antarctica:

• more extreme winters colder summers

• penguins

• NO land animals

• Not owned by countries, managed by treaties

Why is Antarctica so cold?

1. Earth’s tilt (S is tilted away from the sun)

2. Ice packed continent (albedo)

3. High mountains/altitude! Colder!

4. Ice/land surrounded by ocean (ocean currents prevent warm waters from reaching Antarctica)

How is thermohaline circulation formed? What is its significance?

Area around the poles is cold, so water freezes.

When it freezes, it leaves behind a lot of salt, which is super dense

Cold and salty water sinks, and deep water flows through ocean basins

Surface currents return warm water, creating the massive conveyor belt

Distributes energy throughout the world!

What is the most important life form in the Antarctic?

Krill!

What kind of special adaptation does the ice fish have?

Antifreeze glycoprotein in their blood and bodily fluids!

Some have no hemoglobin!

What kind of special adaptations do seal have? Differences in ecology?

1. Blubber v. Fur ; Blubber is warmer than fur and Weddell seals have more of it (found further south than fur seals)

2. Very rich milk for fat production

Which two penguin species are only found in the Antarctic? How much time do they spend in the water?

Emperor and Adele penguins (NOT LAND ANIMALS!! spends 75% of their lives at sea)

What are some adaptations that penguins have?

• Dense feathers (more per surface area)

• Oil preening (spread oil from oil gland to make feathers waterproof and insulated)

• Long strong legs for swimming

What is prey switching and why do penguins do it?

Switching prey by season because competitors (Minke whales) eat a lot more krill. So they switch to fish.

How is climate change affecting krill populations? Penguins? Seals?

Krill

• less sea ice for algae

• warmer waters

Penguins/Seals

• krill for food

• ice as breeding grounds

What is isostacy?

The vertical motion of land (up and down) due to unknown deep earth processes.

19th C. scientists thought this was what created mountains and oceans.

What is the problem with isostacy?

Doesn’t explain continental drift!

Why was Alfred Wegener’s continental drift disputed?

• No reasonable geological way to do it!

• Theory envisioned continents sliding over the mantle yet geophysical data indicated crustal rocks would shatter if pushed!

What is rock magnetism or why are some rocks magnetic

Earth has a magnetic field

When magma containing a lot of iron becomes rock, the magnetic pole position is locked in and the rock retains a record of Earth’s magnetism.

• The magnetic minerals can rotate while the rock is still hot and liquid.

• They line up with Earth’s magnetic field, like tiny compass needles.

• Once the rock cools and hardens, the minerals become locked in place.

• The rock preserves the direction and orientation of Earth’s magnetic field at that time.

What happens to Earth’s magnetic field every few hundred thousand years caused by turbulence in the core? How do we know this?

Earth’s magnetic field flips! Shown by sequences of stacks of lava showing evidence of magnetic polarity reversals

So what actually moved the plates of PANGEA? How do we know this?

plate tectonics!

and essentially seafloor spreading drives plate tectonics

We see this magnetic polarity reversals that were symmetric around all these mid-ocean ridges. Mid-ocean ridges are pushing all the tectonic plates around.

isaldn chains from oceanic hotspots (as plates move, hotspots move too)

1. Heat from Earth’s interior causes hot mantle material to rise and cooler material to sink slowly.

2. Hot material rising beneath Pangaea stretched and weakened the lithosphere.

3. The crust cracked, and magma rose into the openings, beginning continental rifting.

4. New oceanic crust formed between the separating continents, eventually creating the Atlantic Ocean.

What did Marie Tharp do?

She was mapping the entire seafloor when she also found evidence for seafloor spreading

FIRST MAP of the ENTIRE SEAFLOOR!!!!

using sonar

also identified Mid-Atlantic ridge → evidence of seafloor spreading and plate tectonics

What did Tanya Atwater do?

She used the magnetic reversals to explain the San Andreas fault, and suddenly the theory of plate tectonics explained oceans AND the continents.

What are the proportions of salt water, fresh, and ice?

Saltwater: 97%

Ice: 2%

Fresh: 1%

What are the unusual properties of water?

• HIGHLY SOLUBLE (holds a lot of solutes)

• Solid, liquid, gas at Earth’s surface

• Holds heat VERY WELL

• Unusual density response to temp changes (Cold sinks)

What is salinity?

The total amount of dissolved chemicals in the water (1000 g of sea water) (everything that isn’t H2O)

As salinity increases, freezing point…

decreases

As salinity increases, evaporation…

slows

As salinity increases, boiling point…

increases

proportion of chemicals to 1000 g of seawater? what about ppt?

34.4 g salinity per 1000 g

3.5% dissolved salts (35 ppt)

Why is the ocean salty? What chemicals are in it?

1. CHLORIDE 18.98g

2. SODIUM 10.556 g

3. other

How do these chemicals even get into the ocean?

1. Precipitation

2. River runoff

3. Hydrothermal vents

Why is the Ocean not getting any larger and why is it not getting saltier?

It is a steady state! Always in balance

SOURCE = IN

• rivers, rain, hydrothermal vents

SINK = OUT

• minerals turn solid into rocks (precipitation in chemistry)

• Back into ocean crust

• spray and isolation of sea water on land

What is residence time and how is it calculated?

Residence time refers to the amount of time an average molecule stays in a reservoir

amount / delivery rate

What is the residence time of water in the ocean? rivers? atmosphere?

~3,500 years

2 weeks

10 days

Heat v. Temperature

Heat is energy measured in calories

Temperature is the object’s response to input or removal of heat (how rapidly the molecules vibrate)

What is a Heat Capacity?

The heat required to raise the temperature of 1g of substance by 1 degrees Celsius.

What does it mean water has high thermal inertia?

Water tends to resist changes in temperature with a gain or loss of heat! Has a HIGH HEAT CAPACITY

heats up and cools down more slowly

• this is what keeps our planet cool

Water can also take in heat “here” and release it “there”

What is sensible heat?

heat that increases temperature

carried by convection or conduction

What is latent heat and how is water affected by it?

Latent heat = Heat that changes the state of matter without changing its temperature. The energy is hidden in melting, freezing, evaporation, or condensation.

Example: boiling water stays around 100°C while energy changes it from liquid into vapor.

What is the latent heat from ice—water? water—vapor?

Ice—Water = 80 cal

Water—vapor = 540 cal

Why is the ocean blue?

Blue wavelengths penetrates the deepest!