OceansOceans

Importance of Importance of OceansOceans•FoodFood

•RecreationRecreation

•Energy Energy resources (oil & resources (oil & natural gas)natural gas)

•TransportationTransportation

•Salt Salt

Origin of OceansOrigin of Oceans• Early Earth was covered with Early Earth was covered with

volcanoesvolcanoes

• Gases from volcanoes included water Gases from volcanoes included water vaporvapor

• Over thousands of years, the vapor Over thousands of years, the vapor built up in the atmospherebuilt up in the atmosphere

• Eventually it started to rain – a lotEventually it started to rain – a lot

• Oceans formed when this rain filled inOceans formed when this rain filled in low areas called basinslow areas called basins

Contents of Ocean Contents of Ocean waterwater

•96.5% pure water96.5% pure water

•3.5% salts3.5% salts– Sodium chloride, potassium Sodium chloride, potassium

chloride, etc.chloride, etc.– Salinity = how much salt is Salinity = how much salt is

in the waterin the water– Saltier the water, the Saltier the water, the

easier you floateasier you float

Ocean CurrentsOcean Currents•Caused by wind & Earth’s rotationCaused by wind & Earth’s rotation

•Currents move in circlesCurrents move in circles– Coriolis Effect: the shifting of winds Coriolis Effect: the shifting of winds

from their expected paths because from their expected paths because of Earth’s rotation.of Earth’s rotation.•Northern hemisphere - clockwiseNorthern hemisphere - clockwise

•Southern Hemisphere – counter-Southern Hemisphere – counter-clockwiseclockwise

Major Surface CurrentsMajor Surface Currents

Notable CurrentsNotable Currents•Gulf StreamGulf Stream

– Carries warm water from Caribbean Carries warm water from Caribbean across Atlantic towards Englandacross Atlantic towards England

•California California – Carries cold water from Alaska down Carries cold water from Alaska down

Pacific coastPacific coast

•East Australian current (EAC)East Australian current (EAC)– Northern Australia towards Sydney Northern Australia towards Sydney

HarborHarbor

WavesWaves•Caused by Caused by

disturbances disturbances moving across the moving across the surface of watersurface of water

•Size affected by:Size affected by:– Wind primary causeWind primary cause– How long wind blowsHow long wind blows– How much open How much open

water there iswater there is

Wave StructureWave Structure•Crest – High pointCrest – High point

•Trough – Low pointTrough – Low point

•Wave height – Wave height – Distance from crest Distance from crest to troughto trough

•Wavelength – Wavelength – Distance between Distance between crestscrests

TsunamisTsunamis

•Caused by Caused by underwater underwater earthquakesearthquakes

•Wave Wave moves moves outward outward until it hits until it hits landland

TidesTides

•Rise and fall of water levels Rise and fall of water levels each dayeach day

•Caused by:Caused by:– Gravitational pull of MoonGravitational pull of Moon– And Sun as wellAnd Sun as well– Creates bulges of water on EarthCreates bulges of water on Earth

Spring TidesSpring Tides•Occur when sun, moon, and Occur when sun, moon, and

Earth are alignedEarth are aligned

•High tide is higher than usual, High tide is higher than usual, low tides lowerlow tides lower

•Occur twice a month during full Occur twice a month during full and new moonand new moon

Neap TidesNeap Tides• Occur when sun, moon, and Earth Occur when sun, moon, and Earth

are at right anglesare at right angles

• High tides not as high, low tides not High tides not as high, low tides not that low that low

• Occur twice a month during quarter Occur twice a month during quarter moonsmoons