Ocean WavesOcean Waves

Essential Question:Essential Question:How are waves formed and what are the How are waves formed and what are the

characteristics of waves?characteristics of waves?

What is a wave? A Wave is the movement of energy through a

body of water Most waves form when winds blowing across

the water’s surface transmit their energy to the water

How do waves differ? Wave Size:

The size of the wave depends on the strength of the wind and on the length of time it blows

Gentle breeze = small ripples on the surface

Strong winds = larger waves Longer distances that the wind blows

build up bigger waves Wave Energy:

Although waves may appear to carry water towards the shore, the water does not actually move forward

The energy of the wave moves towards the shore but the water remains in place

How do waves move? As the wave passes, water particles move in a

circular path They swing forward and down with the energy

of the wave, then back up to their original position

Winds affects the water at the surface more than it affects the deep water

Below a certain depth, the water does not move at all

What are the characteristics of waves? Crest is the highest part of a

wave The horizontal distance

between crests is the wavelength

Waves are also measured by their frequency, or the number of waves that pass a point in a certain amount of time

The trough is the lowest part of a wave

The vertical distance from the crest to the trough is the wave height

What are the characteristics of waves?

Click picture for animation

How do waves change near the shore? The white capped waves

that crash onto the shore are usually called “breakers”

As the wave approaches the shore the water becomes shallower

The bottom of the wave begins to touch the floor causing the wave to slow down

As the speed decreases, their shapes change

Near the shore, wave height increases and wavelength decreases

When a wave reaches a certain height, the crest of the wave topples

Waves not formed by wind Waves can also be formed below the ocean surface This type of wave is known as a tsunami and is

usually caused by an earthquake beneath the ocean floor

The abrupt movement of the ocean floor sends pulses of energy through the water above it

When tsunamis reach the coast, they can be as devastating as an earthquake on land

How do waves cause beach erosion? From day to day, waves remove sand and

bring new sand at about the same rate Waves shape a beach by eroding the shore in

some places and building it up in others Waves can carve rocky shorelines into tall

cliffs and arches

Self Check:

1. How do waves form?

2. Which wind could give more energy to water- a

strong wind or a gentle breeze?

3. What is the name for the distance between the

crest and trough of a wave?

4. Why do waves slow down close to the shore?

5. What is the source of energy for a tsunami?