TIDESTIDES

DefinitionDefinition

• Tides = periodic rise and fall of large Tides = periodic rise and fall of large bodies of waterbodies of water

• Caused by the gravitational Caused by the gravitational interactions between the Earth and the interactions between the Earth and the Moon and the SunMoon and the Sun

Lunar TidesLunar Tides

• The Moon tries to The Moon tries to pull on Earth to pull on Earth to bring it closer. bring it closer. The Earth is able The Earth is able to hold onto to hold onto everything but the everything but the waterwater

• The oceans bulge The oceans bulge out in the direction out in the direction of the moonof the moon

• Another bulge Another bulge occurs on the occurs on the opposite side. opposite side.

• Two tides occur Two tides occur each day. About each day. About 12hr and 25min 12hr and 25min between two high between two high tides.tides.

Complicating FactorsComplicating Factors

• The Earth and Moon are not static. The Earth and Moon are not static.

• The Earth is not covered in oceans.The Earth is not covered in oceans.

• The oceans are of varying depthsThe oceans are of varying depths

• Friction between the oceans and the Friction between the oceans and the EarthEarth

Effect of the SunEffect of the Sun

• Other objects Other objects influence the Earth’s influence the Earth’s tides.tides.

• The effect of the Sun The effect of the Sun is about half that of is about half that of the Moon.the Moon.

• Particularly large tides Particularly large tides are experienced when are experienced when the Earth, Moon and the Earth, Moon and Sun line up.Sun line up.

• SPRING TIDES: SPRING TIDES: Highest tides. Highest tides. During full and During full and new moon.new moon.

• NEAP TIDES: NEAP TIDES: Weaker tides. Weaker tides. During first and During first and third quarterthird quarter

Tides in the Bay of FundyTides in the Bay of Fundy

Hopewell RocksHopewell Rocks

The Tidal BoreThe Tidal Bore

• The leading The leading edge of the edge of the incoming tide incoming tide forms a wave of forms a wave of water that water that travels up a travels up a river or narrow river or narrow bay against the bay against the direction of the direction of the current.current.

Standing WavesStanding Waves

• A wave that remains in a constant A wave that remains in a constant position.position.– The medium is moving in the opposite The medium is moving in the opposite

direction to the wave.direction to the wave.

The Annapolis Tidal Generating The Annapolis Tidal Generating StationStation

• Uses the massive Uses the massive movements of the movements of the water in the Bay of water in the Bay of FundyFundy

• Creates enough Creates enough energy to power energy to power 5000 homes.5000 homes.

• The only tidal power The only tidal power station in North station in North AmericaAmerica

Earth’s RotationEarth’s Rotation

• Tidal interactions Tidal interactions have slowed have slowed Earth’s rotational Earth’s rotational period.period.

• Eventually (billions Eventually (billions of years) Earth and of years) Earth and Moon will have the Moon will have the same rotational same rotational period (27.3 days)period (27.3 days)

EvolutionEvolution

Resources• http://www.lcsd.gov.hk/CE/Museum/Space/EducationResource/Universe/framed_e/lecture/ch06/imgs/tides.jpg• http://www.enchantedlearning.com/subjects/astronomy/moon/Tides.shtml• http://www.jochemnet.de/fiu/tide2.jpg• http://home.hiwaay.net/~krcool/Astro/moon/moontides/• http://www.physicalgeography.net/fundamentals/images/earth_moon.jpg• http://photoclub.canadiangeographic.ca/photos/rosco-photo/images/43243/500x335.aspx• http://static.howstuffworks.com/gif/ocean-current-6b.jpg• http://www.huntsmanmarine.ca/images/tides_1rd.jpg• http://upload.wikimedia.org/wikipedia/commons/5/54/Bay_of_Fundy.jpg• http://www.canadacool.com/COOLFACTS/NOVA%20SCOTIA/NOVASCOTIAPHOTOS/annapolis7low.jpg• http://www.intute.ac.uk/sciences/worldguide/satellite/2559.jpg• http://www.srh.noaa.gov/jetstream/ocean/images/bayoffundy.jpg• http://www.raftingcanada.ca/• http://cord.org/cm/leot/course01_mod07/loet01-07-06new.gif• http://www.canada-maps.org/nova-scotia-map.htm• http://grant7.typepad.com/trilogy/images/tidal%20pool.bmp• http://www.zoology.ufl.edu/personal/grad/jhavird/Picture/killifish-pics-(1)-(optimal).jpg• http://www.ucmp.berkeley.edu/vertebrates/sarco/lungfish1.jpg• http://csep10.phys.utk.edu/astr161/lect/time/tides.html• http://csep10.phys.utk.edu/astr161/lect/time/tides.html• http://en.wikipedia.org/wiki/Tidal_bore• http://www.physicalgeography.net/fundamentals/images/earth_rotation.jpg• http://www.michaeltaylor.ca/Culture/hopewell-low.jpg• http://thomonthenet.com/Maritimes2002/123a.jpg