9.1 oceans. the blue planet 71% of earth’s surface is covered by oceans and seas. the science that...

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9.1 Oceans

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9.1 Oceans

The Blue Planet71% of Earth’s

surface is covered by oceans and seas.

The science that studies the world ocean is called oceanography.

Question: What’s the difference between an ocean and a sea?

Answer: Seas are partially surrounded by land.

Geography of the OceansWorld Ocean is divided

into 5 ocean basinsPacific, Atlantic,

Arctic, Indian, and Southern Oceans Question:

What oceans are almost entirely in the Southern Hemisphere?

Pacific Ocean is the largest and deepest.

Arctic is the smallest and most shallow.

Answer: Indian and Southern Oceans

Topography is the shape of the land or ocean floor.

Ocean floor topography is like land: Volcanoes, Mountains, Plateaus

Ocean Topography

Mapping the Ocean FloorBathymetry measurement of

ocean depths and charting topography of ocean floor.

First Study of World Ocean was HMS ChallengerSailed under British FlagDecember 1872 – May 1876First research ship

TechnologySONAR (Sound Navigation and Ranging)

Before sonar, ocean floor was believed to be flat and smooth

Uses sound waves bounced of the ocean floorFirst created in 1906 by Lewis Nixon to detect

icebergs.Technology advanced to detect submarines during

WWI.

Question:What are other uses for SONAR?

Answer: Locate and monitor ocean animals like whales.

SATELLITESSatellites bounce

microwaves (radio waves) off the ocean surface

Technology

SUBMERSIBLESSmall underwater

crafts, both manned and unmanned

March 25, 2012 James Cameron reached a record 7 miles below the surface of the ocean at the Marianna Trench (deepest part of the ocean)

SALINITYSalinity - total amount of

solid substance dissolved in water.Units are parts per

thousandAverage salinity of the

ocean is 35/1000 (3.5 %)

Sources of Sea Salt (NaCl – Common table salt):Chemical weathering of

rocks on landUnderground volcanic

eruptions (gasses)

Variation in SalinityLow salinity - fresh

water from glaciers, melting sea ice, large rivers

High salinity - evaporation removes fresh water; formation of sea iceQuestion:

Would you expect the salinity at a river delta to be higher or lower than in the middle of the ocean? Why?

Answer: lower because fresh water is mixing with the salt water.

More solar radiation = Warmer WaterAt equator At water’s surface

Less solar radiation = Colder WaterNear polesIn deep water

OCEAN TEMPERATURE VARIATIONSOcean surface water temperature varies with

the amount of solar radiation (heat)

Thermocline – A layer of water in which there is a rapid change in temperature with depth.low latitudeAt 300-1000 m temperature is just

above freezingCreates barrier between marine

lifeIsothermal - near freezing from

surface to floor high latitude

Thermocline and Isothermal

Left side hints: therm = heat, iso is even/ same, cline = gradient

OCEAN DENSITY VARIATIONS

Remember: Low density on the topHigh density on the

bottomAs salinity increases,

density increases As temperature

decreases, density increases

Question:Where would you find the most dense water?

Answer: High latitude! Near freezing with high salinity due to sea ice.

3 OCEAN LAYERSSurface zone – mixed

density & temperature

waves, sun’s energy, constantly mixing

Transition zone (Pycnocline) –moves water from warm surface layer above to cold layer below

Deep zone – No sunlight, water temperature just above freezing & density is high