Ocean Motion Notes - Mrs. Smit's Science...

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