Oceanography Chp 1

• The Ocean, Uses


  • Transportation
  • Waste Removal
  • Electricity
  • Communication
  • Food
• Newgrange, Ireland
• The Ocean, The Source

  • Moderates temperatures
  • Influences weather
  • Source of food (2%)
  • 1/3 of petroleum and natural gas from ocean floor
  • 1/2 world's population lives on the coast
• Approximately 50% of world population lives within 240 kilometers of the coastline
• The ocean is a single entity that covers 71% of the Earth's surface
• Breakdown of Total Water

  • 1.7% Ice on land
  • 0.8% groundwater
  • 0.007% surface water
  • 0.001% atmospheric water
  • 2.5% Freshwater
• Ocean Statistics


  • Surface Area: 361 million square kilometers of Earth's surface
  • Average depth: 3796 m
  • Volume: 1.37 billion cubic kilometers
  • Temperature: 3.9 degrees Celsius on average
  • Mass: 141 billion billion metric tons

  
• Mauna Kea is the tallest mountain from seabed and Mariana Trench is the deepest spot in the ocean

  
• The ocean is 4.5 times deeper than the elevation of land

  
• Oceanography


  • Interdisciplinary science
  • Includes: Physical oceanographers, Marine Biologists, Chemical oceanographers, Marine Engineers, Marine Geologists
• How the universe began

  1. Big Bang 13.7 billion years ago

  2. Early Universe cooled as it expanded

  3. 1 million years after the bang temperatures cooled allowing hydrogen to dominate

  4. 1 billion years after the bang galaxies and stars started to form

  
• The Wilkinson Microwave Anisotropy Probe mapped the Cosmic Microwave Background radiation and determined the universe to be 13.77 billion years old to within a half percent
• The Planck mission mapped the sky using 9 wavelengths to get a more precise view and found galaxies cluster and early ones have faster rate of star formation
• Galaxies


  Huge rotating clumps of stars, dust, gas and other debris held together by gravity
• Our solar system orbits the Milky Way galaxy's core, taking 230 million years for one orbit at a speed of 280 km/second
• Recent evidence shows that black holes may have come before galaxies
• Formation of Stars


  1. Starts as spinning nebula

  2. Shrinks and heats up under its own weak gravity

  3. Cloudlike Sphere flattens and condenses into a knot of gases (protostar)

  4. Heats up to 10 million degrees Celsius

  5. Fusion forms Helium

  6. Gives off energy

  7. Energy stops the star's shrinkage

  8. Becomes stable

  9. Eventually uses up its fuel and dies
• Death of a Medium Mass Star

  1. When it begins to consume carbon and oxygen atoms, its energy output slowly rises and its body swells to a stage called the red giant

  2. Higher core temperatures permit formation of atoms up to the mass of iron
• Death of a Massive Star

  1. Dying phase begins when its core, depleted of hydrogen, collapses on itself

  2. Rapid compression causes the star's internal temperature to soar

  3. When infalling material can no longer be compressed the energy of the inward fall is converted to a cataclysmic expansion called a supernova
• Nebular Hypothesis


  Our Solar system condensed from a cloud of dust and gas called a nebula, with gravity being the key force in condensing this solar nebula
• Formation of the Solar System

  1. Solar nebula was affected by a shock wave that caused the condensing mass to spin and absorbed some heavy atoms from a passing supernova remnant

  2. Solar nebula consisted of 75% hydrogen, 23% helium and 2% other heavier elements, gases, dust and ice

  3. Material in centers became protosun, outer material formed planets through accretion
• Requirements of a Planet

  • It must be in orbit around the Sun
  • It must be large enough that it takes on a nearly round shape for its orbit
  • It has cleared its orbit of other objects
• Density Stratification


  1. Denser elements like iron and nickel pulled by gravity to the inner core

  2. Lighter minerals such as silicon magnesium, aluminium and oxygen-bonded compounds rose to surface to form Earth's crust

  3. Process lasted approximately 100 million years
• Planet grew by accretion, with particles like meteors and asteroids hitting the surface and helping to partially heat up and melt Earth's surface through gravitational compression and decay of radioactive elements
• Layers of Earth


  • Inner Core
  • Outer Core
  • Mantle
  • Crust
• Earth's Past Atmospheres


  1. First atmosphere was carbon dioxide, nitrogen and water vapor with traces of ammonia and methane

  2. Radiation stripped away first atmosphere and the second was formed by outgassing

  3. The third atmosphere that we know today began 3.5 billion years ago and gradually altered to current composition (nitrogen and oxygen)
• Outgassing


  Volcanic venting of volatile substances including water vapor
• Earth had first solid surface about 4.5 billion years ago, and the ocean formed later (approx 4 billion years ago) when Earth's surface was cool enough to allow clouds of steam and water vapor to condense and rest on the surface
• Biosynthesis


  Evolution of living organisms from simple organic building blocks
• Conditions needed for biosynthesis: Absence of oxygen, Gases similar to Earth's early atmosphere, Light, Heat. Where?: Deep ocean near vents
• Photosynthetic Bacteria are the earliest known life, 3.5 billion years old
• In 5 billion years the Sun will start to die, and in 1 billion years it will reach the Red Giant stage and engulf Earth's orbit, with Earth's components potentially being recycled into a new star system and planets
• Requirements for an Ocean World

  • Must move in a nearly circular orbit around a stable star
  • The distance of the planet from the star must be just right to provide a temperature environment in which water is liquid
  • Must be single sun otherwise orbital year would have irregular periods of intense heat or cold
  • Materials accreted to form planet must have included both water and substances capable of forming a solid crust
  • The planet must be large enough that its gravity will keep the atmosphere and ocean from drifting off into space
• Europa, a moon of Jupiter, has 40 times more water than Earth and an 8km thick surface of ice, with an ocean below kept liquid by heat escaping the moon's interior
• Mars may have had an ocean in warmer times between 3.2 billion and 1.2 billion years ago, with a carbon dioxide rich atmosphere like early Earth keeping it warm
• Photographs suggest young gullies on Mars, similar to water running over dry land creating fan like patterns, with the water potentially warmed by volcanic heat within Mars
• Titan, Saturn's largest moon, has photographs showing lakes and rivers flowing in channels
• Reasons for Voyaging and Discovery

  • Ocean transportation
  • Access to food supplies
  • Trade
• Cretans or Phoenicians were the first regular ocean traders, approximately 1200 BCE
• Mediterranean traders were the first cartographers, using latitude and longitude for positioning