Waves and TidesWaves and Tides

WavesWaves

Everyone has seen waves on a lake or ocean. But what are

they? Waves are actually energy.

Energy, not water, moves

across the ocean's surface.

http://www.virtualnjshore.com/tbwaves.html

Wavelength

Wave Height

Crest

Trough

Still Water

Wave Parts

What causes waves?What causes waves?

Waves are caused by energy being Waves are caused by energy being transferred into the ocean watertransferred into the ocean water

The energy come from:The energy come from:

1.1. Wind- the wind is air that moves by Wind- the wind is air that moves by energy from the sun.energy from the sun.

2.2. Undersea Earthquakes- they can Undersea Earthquakes- they can also put energy into the wateralso put energy into the water

What determines the size of What determines the size of a wave?a wave?

If waves carry energy, what has more energy, a If waves carry energy, what has more energy, a big wave or a small wave?big wave or a small wave?

If winds cause waves, will stronger ,faster If winds cause waves, will stronger ,faster winds give wave more or less energy? winds give wave more or less energy? (activity)(activity)

If wind blows for a long time will the waves If wind blows for a long time will the waves have more or less energy?have more or less energy?

If wind the wind blows over a small part of the If wind the wind blows over a small part of the ocean what will happen to the wave’s energy?ocean what will happen to the wave’s energy?

- The size of the wave depends on the The size of the wave depends on the amount of energy transferred into the amount of energy transferred into the water.water.

- The amount of energy depends on 3 The amount of energy depends on 3 things.things.

1. Speed of the wind1. Speed of the wind

2. How long the wind blows2. How long the wind blows

3. The distance over which it blows3. The distance over which it blows

If any of these increases, the size of the If any of these increases, the size of the waves will also increasewaves will also increase

Why are waves Why are waves importantimportant

Storm SurgeStorm Surge

A storm surge is a A storm surge is a rise in sea level near rise in sea level near the shorethe shore

It is caused by It is caused by strong winds fro a strong winds fro a storm like a storm like a hurricane.hurricane.

http://www2.sunysuffolk.edu/mandias/38hurricane/storm_surge_maps.html

TsunamiTsunamiA tsunami is a A tsunami is a powerful wave (or powerful wave (or group of powerful group of powerful waves) cause by the waves) cause by the shaking of the shaking of the ground under ground under oceans. Earthquakes oceans. Earthquakes and volcanoes can and volcanoes can cause tsunamis.cause tsunamis.

Effects of the Asian Effects of the Asian TsunamiTsunami

In 2004, an earthquake occurred under the Indian ocean.

Wrap-up and Exit TicketWrap-up and Exit Ticket

Trough

Word Bank:

Waves, wavelength, crest, wave height, wave speed.

Consists of a

Whose size determines

and the distance between two of these is the

Which is used to calculate

TidesTides

A tide is a rise or fall of the A tide is a rise or fall of the ocean’s surfaceocean’s surface

Tides are caused mostly by the pull of gravity Tides are caused mostly by the pull of gravity of the moon. of the moon.

The sun’s gravity also affects a tide just not as The sun’s gravity also affects a tide just not as much as the moon’smuch as the moon’s

High tide in Nova Scotia

Low tide in Nova Scotia

Why we study tidesWhy we study tides

Tides are importantTides are important- When When buildingbuilding beach properties. beach properties.- Animals:Animals: Some animals like sea turtles Some animals like sea turtles

only lay their eggs on certain tides (page only lay their eggs on certain tides (page 368)368)

- SafetySafety of humans of humans- For EnergyFor Energy: Scientists can use : Scientists can use

movement of water during tides to movement of water during tides to produce energy (the enegery of the water produce energy (the enegery of the water powers generators to produce electricity)powers generators to produce electricity)

Tides – how it worksTides – how it works

The moon can add to the pull of the sun and make higher tides.

The moon can work against some of the gravitational pull of the sun and make the tides lower.

http://curious.astro.cornell.edu/images/tides.jpg

High TidesHigh Tides

High Tides occur when the oceans High Tides occur when the oceans water has risen as far as it will gowater has risen as far as it will go

-This happens when the oceans on -This happens when the oceans on Earth are facing the moonEarth are facing the moon

Low TideLow Tide

When the ocean water has fallen as When the ocean water has fallen as low as it can go on shorelow as it can go on shore

It happens when the moon is It happens when the moon is sideways from the shoresideways from the shore

Spring TideSpring Tide

During this tide the sun, moon, and Earth are During this tide the sun, moon, and Earth are aligned so gravity from the sun and moon pulls aligned so gravity from the sun and moon pulls the oceansthe oceans

This happens during a new moon or full moon.This happens during a new moon or full moon.

Neap TidesNeap Tides

This is when the ocean levels on land This is when the ocean levels on land are as low as they can go.are as low as they can go.

It only happens during a First It only happens during a First Quarter new and a Last Quarter Quarter new and a Last Quarter moon. moon.

Tide TimingTide Timing

The time between 2 high tides is 12 The time between 2 high tides is 12 hourshours

The time between 2 low tides is 12 The time between 2 low tides is 12 hourshours

There is a period of 6 hours between There is a period of 6 hours between a high tide and a low tidea high tide and a low tide