Ocean Motion Notes Chapter 13 & 14
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Ocean Motion Notes
Chapter 13 & 14
What is a Wave?
• Wave: movement of energythrough a body of water
How are Waves Caused?
• Caused mostly by wind
–Wind blowing on the water transmits energy to the water
Size of Wave
–Depends on the strength of the wind
–Depends on the length of time wind blows
–Depends on the distanceover which wind blows
Wave Energy
–Energy moves towardthe shore but waterdoes not
Water Motion
–Surface
•Circular motion
–Deep
•Smaller circles
–Very deep
•No motion (Waves)
Characteristics of Waves
• Wavelength: horizontal distance between crests
–Long wavelength (rolling)
Classification of Waves
–Short wavelength (choppy)
Characteristic of Waves
• Crest: the highest point of the wave
• Trough: the lowest point of the wave
Characteristic of Waves
• Wave Height: the vertical distance from the crest to the trough
• Frequency: the number of waves that pass a point in a certain amount of time.
Wave Action
• How waves change near the shore
• Breakers: White capped waves that crash onto shore
Wave Action
–Friction between ocean floor and water causes wave to slow down.
•Speed decreases, shapechanges
–Wave height increases
–Wave length decreases
Wave Action
–Surf: Wave breaks onto the shore
–Undertow: Water rushesback to the ocean
Tsunamis
• Tsunamis: Caused by earthquakebeneath (under) the ocean floor
• In deep water: No problem– Wave length 200 km
– Wave height less than 1 meter
Tsunami• Near shore…
HUGE Problem!–Friction causes water to “pile up”
–Wave height 20 meters (5 stories)
How waves affect the shore
• Long shore drift: Water washes sand straight down the beach
–Sand
creates
a sandbar
How waves affect the shore
• Rip Currents: Water breaksthrough sand bar
–Water flows back to the ocean floor
•Very dangerous to swimmers
Waves and beach erosion
• Waves shape a beach by eroding the shore in some places and building up in others
Waves and beach erosion
• Barrier Beaches: Natural land form protects the shore line
–Runs parallel to the beach
•Waves strike barrier beach instead of shore line
Waves and beach erosion
• Sand Dunes: Wind blown sand makes beach more stable
–Plants help keep sand in place
Waves and beach erosion
• Groins: man-made wall of rockor concrete
–Sand build up
against the wall
Tides
• Daily riseand fall of the Earth’s ocean
• Caused by Gravity
Tides
–Spring Tide Neap Tide
Ocean Water Chemistry
• The Salty Ocean
• Salinity: How salty the ocean is
–The amount of dissolved salt in the water
Ocean Water Chemistry
•35 grams of salt in 1 kilogram of water
Water
96.5%
Dissolved Salts 3.5%
Ocean Water Chemistry
•NaCl (Sodium Chloride) most abundant salt in the ocean
–NaCl Breaksdown into Na ions and Cl ions
Variations in Salinity
–Lower near the surface of the ocean
–Lower near the mouth of large rivers
–Evaporation increases salinity (Ex. Dead sea)
–Higher near the poles
Effects of Salinity
–Ocean water does not freeze easily
–Seawater is more dense so it has greater buoyancy
•things float
better in it
Other Ocean Properties
• Temperature
–Cold water is more dense so it sinks
–Warm water rises to the surface
Other Ocean Properties
• Gases
–CO2 and O2
•CO2 is more abundantthan O2
Other Ocean Properties• Changes with
Depth
–Decreasing Temperature
•As you go down (descend) temperature decreases
Changes with Depth
•Three zones
–Surface Zone (Warmest)
–Transition Zone
–Deep Zone
Changes with Depth–Increasing Pressure
•As you go down in the ocean, pressure increasescontinuously
Changes with Depth
• Submersible- underwatervehicle built to resist pressure
The Ocean Floor
The Ocean Floor
Currents and Climate
Surface Currents
• Affects water to a depth of several hundred meters
• Driven mainly by Wind
Currents & Climate
• Coriolis Effect: Since the earth is round, the wind curves–Northern Hemisphere:
Curve to the right
–Southern Hemisphere:
Curve to the left
Currents & Climate
• Gulf Stream: Largest most powerful current
Effects on Climate
• Warm water from the equator to the poles
• Cold water from the poles goes toward the equator
Effects on Climate
–Surface current warms or cools the air above it
–Influences the climate of the land near the coast
Effects on Climate
• El Nino: Causes shifts in the weather patterns
–Can cause flooding
Deep Currents
• Deep currents move and mixwater around the world.
• Deep currents carry coldwater from the poles toward the equator
Deep Currents
–Salinity increases near the poles
•Increased Salinity Increased Density
–Cold water moves along the ocean floor
Deep Currents
• Surface currents carry warmwater toward the poles.
• Affected by Coriolis Effect
–Currents curve around the world
Upwelling
• Upwelling: the movement of cold water upward from the deep ocean
Upwelling
• As winds blow away the warm surface water, cold water rises to replace it.
• Brings microorganisms and nutrients back to the surface
Conservation of Waterin theworld
WaterConservation in the world
Water Conservation at Home
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