WavesWaves

Chapter 14 Section 3Chapter 14 Section 3

By Caroline Hollar, Hannah Greenwald, By Caroline Hollar, Hannah Greenwald, Annie Klopp, and Shannon ConsoloAnnie Klopp, and Shannon Consolo

What is a Wave?What is a Wave?

A wave is a A wave is a traveling traveling disturbance that disturbance that carries energy.carries energy.

It is the energy It is the energy that moves, not that moves, not the medium (stuff the medium (stuff or material) the or material) the wave is passing wave is passing through.through.

MediumMedium

Medium the Medium the material of which a material of which a wave moves, (for wave moves, (for an ocean wave it is an ocean wave it is the ocean)the ocean)

In a rope wave it is In a rope wave it is the rope.the rope.

In sound waves it In sound waves it is the air.is the air.

Types of WavesTypes of Waves Compressional Compressional

(longitudinal): the (longitudinal): the energy travels parallel energy travels parallel to the direction of to the direction of travel. Example: travel. Example: Sound waves, P Sound waves, P waves. (Slinky wave)waves. (Slinky wave)

Transverse: the Transverse: the energy is at right energy is at right angles to the direction angles to the direction of travel. Example: of travel. Example: rope, water, and S rope, water, and S waves.waves.

Parts of WavesParts of Waves There are several There are several

main parts of a main parts of a wave…wave…

There is the crest, the There is the crest, the point at the toppoint at the top

The trough, the point The trough, the point at the bottom, at the bottom, (opposite of crest)(opposite of crest)

Wavelength, the space Wavelength, the space between two crests between two crests measured in metersmeasured in meters

Amplitude: the Amplitude: the distance from the 0 distance from the 0 line to the crest or line to the crest or trough (energy)trough (energy)

Wave height: distance Wave height: distance from trough to crestfrom trough to crest

---wavelength----

mediumtrough

crest

Wave direction

Parts of a waveParts of a wave

How Waves FormHow Waves Form The wind blows across the water in open ocean, giving The wind blows across the water in open ocean, giving

the water the winds energy. the water the winds energy. The size of the wave depends on the The size of the wave depends on the speed of the speed of the

windwind, its , its durationduration and the and the fetchfetch (distance the wind acts (distance the wind acts on the wave) that hits it and how on the wave) that hits it and how ..

Without the wind, the ocean would be completely flatWithout the wind, the ocean would be completely flat

Forming WavesForming Waves

These are the steps in forming a These are the steps in forming a wave…wave…

1) wind speed1) wind speed 2) wind duration (time) 2) wind duration (time) 3) the area over which the wind blows 3) the area over which the wind blows

((fetchfetch)) The more of each, the bigger the wave, The more of each, the bigger the wave,

as more and more energy gets added to as more and more energy gets added to the wavethe wave

Section 3 Waves

Formation and Movement of Ocean Waves

Chapter 14

Click below to watch the Visual Concept.

Visual Concept

Wave Formation and Movement

Most waves form as wind blows across the water’s surface and transfers energy to the water.

As the energy moves through the water, so do the waves. But the water itself stays behind, rising and falling in circular movements.

Why Waves BreakWhy Waves Break•As waves move closer to land the medium changes because shallow water is different than deep water.

• In the shallow water the sand at the bottom catches the wave and eventually slows the bottom part of the wave down.

• The top part of the wave is still moving faster, so it rides up on top of the slower moving water.

•Eventually it gets too tall and falls over, breaking on the beach.

•So wave height increases while the wavelength decreases

As deep-water waves become shallow-water waves, the water particles slow down and build up. This change forces more water between wave crests and increases wave height. Gravity eventually pulls the high wave crests down, which causes them to crash into the ocean floor as breakers. The area where waves first begin to tumble downward, or break, is called the breaker zone. Waves continue to break as they move from the breaker zone to the shore. The area between the breaker zone and the shore is called the surf.

How waves Change near How waves Change near shoreshore

Types of Waves, continued• Shore Currents When waves crash on the

beach head-on, the water they moved through flows back to the ocean underneath new incoming waves.

• This movement of water forms a subsurface current that pulls objects out to sea and is called an undertow.

Types of Waves, continued Storm Surges are

local rises in sea level near the shore that are caused by strong winds from a storm.

Winds form a storm surge by blowing water into a big pile under the storm. As the storm moves onto shore, so does the giant mass of water beneath it.

Longshore DriftsLongshore Drifts When waves come to When waves come to

shore, sometimes the waves shore, sometimes the waves water comes to the beach at an water comes to the beach at an angle and carries sand angle and carries sand

with itwith it A longshore drift occurs when A longshore drift occurs when

this happensthis happens This pushes sand further down This pushes sand further down

the beachthe beach So the beach gets eroded in the So the beach gets eroded in the

direction of the current, and direction of the current, and built up further down the beachbuilt up further down the beach

When the waves move slower When the waves move slower they put the sand on the they put the sand on the underwater slope, making a underwater slope, making a sandbarsandbar

Longshore Drift

Rip CurrentsRip Currents Rip Current- a rush of water that Rip Current- a rush of water that

flows rapidly back to the sea flows rapidly back to the sea through one narrow opening.through one narrow opening.

When a sandbar gets larger, it When a sandbar gets larger, it traps the water flowing on the traps the water flowing on the shore.shore.

Water sometimes breaks Water sometimes breaks through the sand bar and flows through the sand bar and flows back down which forms a rip back down which forms a rip current.current.

Rip currents are very dangerous.Rip currents are very dangerous. When you get caught in a rip When you get caught in a rip

current you should swim parallel current you should swim parallel to the shore until you get out of to the shore until you get out of the current.the current.

Like we said before, it carries Like we said before, it carries water out to sea, and can take water out to sea, and can take you with it.you with it.

TsunamiTsunami

Large waves caused when a large body of Large waves caused when a large body of water is moved up and down.water is moved up and down.

Caused by underwater earthquakes, volcanic Caused by underwater earthquakes, volcanic eruptions, landslides or meteorite/comet eruptions, landslides or meteorite/comet impacts.impacts.