coach williams room 310b. physical oceanography
TRANSCRIPT
Objectives:◦ Identify methods used by scientists to study
Earth’s oceans◦ Discuss the origin and composition of the oceans◦ Describe the distribution of oceans and major
seas
Section 15.1: The Oceans
Sonar: SOund NAvigation and Ranging” Mapping ocean floors Side-scan sonar: angles Satellites: monitor water temp/ waves
Modern Oceanography
Earth: 4.6 billion years old◦ Ocean sedimentary rock ◦ Igneous rock- lava chilled quickly = water
Where did ocean water come from?◦ Meteorites colliding release water◦ 0.05% of meteorites are water◦ Volcanism: water vapor
Origins of Oceans
Oceans: 97% of Earth’s water Freshwater/glaciers: 3% Sea Level: level of the ocean
◦ Ice makes sea levels vary◦ Sea floor rising/falling
71% of planet is covered by oceans Major Oceans: Pacific, Atlantic, Indian Other oceans: Arctic & Antarctic Seas: smaller than oceans and usually land-
locked
Distribution of Earth’s Water
Objectives:◦ Compare/contrast the physical and chemical
properties of seawater◦ Explain ocean layering◦ Describe the formation of deep-water masses
Section 15.2: Seawater
96.5% water & 3.5% dissolved salt (NaCl) Salt is metal & group17 on periodic table Salinity: amount of dissolved salt
◦ Average: 35ppt (parts per thousand)◦ Lower: polar regions, river/ocean, high
precipitation◦ Higher: low precipitation/high evaporation
Salt: Volcanism, weathering/rivers Dissolved gasses: O, N, CO2
Salt balance: precipitate, ocean spray, animals
Chemical Properties of Seawater
Density: more dense than pure water >1◦ Salinity, temperature
Freezing point lowered (-2°C) Darkness: ocean water absorbs light (100m)
Physical Properties of Seawater
Range of surface temp.: -2°C through 30°C (Avg=15°C)
Depth & temp.: deeper = colder Temp. Profile: plots temp. with depth 3 Layers (based on temp./density)
◦ Surface layer◦ Thermocline: rapidly decreasing temp.◦ Bottom layer
Ocean Layering
Warm tropic water rises Polar waters sink 3 Ocean Masses:
◦ Antarctic Bottom Water◦ North Atlantic Deep Water◦ Antarctic Intermediate Water
Water Masses
Objectives:◦ Describe the physical properties of waves◦ Explain how tides form◦ Compare/contrast various ocean currents
Section 15.3: Ocean Movements
Wave: movement that carries energy Caused by wind Water moves up and down; energy moves
forward
Waves
Crest: tallest part Trough: lowest part Wavelength: distance between wave Wave base: how deep water is disturbed
◦ ½ of wavelength Speed of wave affected by wavelength
◦ Speed = wavelength x frequency Wave height: distance from crest to trough
Wind speed Wind duration Fetch: how much open water
Wave Characteristics
Breakers: collapsing waves Friction with bottom slows water down Faster waves catch slower moving water Faster water at top Shapes shoreline
Breaking Waves
Periodic rise/fall of sea level◦ High Tide: highest level◦ Low Tide: lowest level
Tidal range: difference between two levels
Tides
Gravitational pull: Earth, Moon, Sun Gravity depends on mass and distance
◦ Sun: larger mass (Solar Tides)◦ Moon: closer (Lunar Tides)
Spring tides: Sun/Moon/Earth aligned◦ Tides are higher/lower than normal
Causes of Tides
Density currents: ◦ Caused by density differences (salinity/temp.)◦ Slow moving
Surface currents:◦ Wind driven currents◦ Top 100m◦ Faster◦ Predictable patterns
Gyres: circular current systems
Ocean Currents
Gyres