Waves, Currents, and Tides

Waves, Currents, Tides (WCT) Cornell Notes

Key Terms Notes

Summary:

Engage

• Study Jams: Waves and Currents• The class “WAVE”

– How did we move?– Did we actually move around the classroom

with the wave?

Introduction to Waves

Waves• A disturbance which moves

through or over the surface of a fluid

• Mostly caused by windsCaused by:• Wind• Earthquakes• Gravitational force of the

Moon and Sun.

• Form of great energy

Wave Characteristics

• Parts of a Wave– Crest = high point

– Trough = low point

– Height = vertical distance from crest to trough

– Wavelength = Horizontal distance between crest to crest or trough to trough

OCEAN WAVES

• A wave is the movement of energy through water.

What causes waves?

• Waves form from wind• Waves form out in the open ocean,

and travel inwards to the shore.

What are the effects of waves?

• Waves can erode and deposit sediment, changing the shape of the beach

BIGGER winds create BIGGER waves

Tsunamis

• Tsunamis (underwater waves) are giant ocean wave caused by earthquakes, landslides, and volcanic eruptions beneath the ocean floor

– As tsunamis approach the shore, the waves come closer together and grow into a mountain of water

Tsunami Waves

• The energy from waves can carry materials to the seashore. Beaten-up pieces of shells and rocks can be carried to a beach by pounding waves. In Australia, a huge amount of sea foam was once carried in!

Wave Movement

• When a wave passes through the ocean, individual water molecules move up and down but they do not move forward or backward.

Tides• Tides are the movement of ocean water

at the shore when it rises and falls during the day

• High and Low tides occur 2 times per day

Types of Tides

– 2x’s/month

•Spring Tide - Moon and sun are in direct

line with one another- Results in unusually high

tidal range - Tidal Range = vertical distance

between high & low tides

• Neap Tide– sun and moon are at right

angles

– Pulls cancel each other out – causes a weak pull

– unusually low tidal range

– 2 x’s / month

What causes tides?

• The gravitational pull of the moon and sun on Earth’s water

• High tides occur when the moon and sun are lined up on the same side of the Earth

What are the effects of Tides?

• High tides: Water level is high on shore• Low tides: Water level is low on shore

Currents

What are ocean currents?http://www.brainpop.com/science/earthsystem/oceancurrents/

• Ocean Current: mass of ocean water moving from one place to another.

• 2 types of currents: – Surface current– Thermohaline (Deep water)

current

What causes Surface Currents?

• Surface currents: horizontally flowing currents caused by global and seasonal winds

• Usually warmer-water• Direction of currents is

caused by Coriolis Effect

• http://www.classzone.com/books/earth_science/terc/content/visualizations/es2401/es2401page01.cfm?chapter_no=visualization

Coriolis Effect

• Coriolis Effect: Earth’s rotation causes objects in the N. hemisphere move clockwise, objects in S. hemisphere to move counterclockwise

Demo: Deep Ocean Currents

• http://www.youtube.com/watch?v=I8kToTROCHA

What causes deep ocean currents? Temperature = least dense = floating water

Temperature = more dense = water sinks

• Thermo = heat, haline = salt

Deep ocean currents are vertical currents caused by differences in density and temperature ( water masses rise and fall)• Usually colder water

This diagram is a view of the deep ocean currents of the world.

What are the effects of currents?

• Surface currents form large circular patterns called gyre.

• Currents affect the climate of a location– Warm-water

currents warm up climate, cold water currents cool down climate

“Global Conveyor Belt”

• When combined with surface currents it results in a conveyor-belt movement of water around the globe!

Check for Understanding

• When the temperature of these currents decrease, what will happen to the density?

The density will increase

• Will cold ocean water sink toward the bottom or rise to the surface?

Cold water will sink the bottom because it is more dense (Convection!!!!)