Waves Currents and Tides Waves Currents Tides WCT

Waves, Currents, and Tides

Waves, Currents, Tides (WCT) Cornell Notes Key Terms Summary: Notes

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 winds Caused 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. Beatenup 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 • 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 – 2 x’s/month

• 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

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. co m/watch? v=I 8 k. To. TROC HA

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? • Currents affect the climate of a location – Warm-water currents warm up climate, cold water currents cool down climate • Surface currents form large circular patterns called gyre.

“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!!!!)