OceansOceans

The Last FrontierThe Last Frontier

Ocean FactsOcean Facts• About 71% of Earth’s surface is covered by waterAbout 71% of Earth’s surface is covered by water

• Average depth of the Pacific Ocean = 4,638 mAverage depth of the Pacific Ocean = 4,638 m

• Average depth of the Atlantic Ocean = 3,872 mAverage depth of the Atlantic Ocean = 3,872 m

• Average temperature = 3.9Average temperature = 3.9°C (39.0°F)°C (39.0°F)

• Age of oceans = 4 billion yearsAge of oceans = 4 billion years

Salinity in OceansSalinity in Oceans

– Total amount of dissolved Total amount of dissolved solids expressed in grams in 1 solids expressed in grams in 1 kg of waterkg of water

•Average salinity in oceans = 35 Average salinity in oceans = 35 ‰‰

• Salinity variationsSalinity variations– Due to differences in local Due to differences in local

rates of evaporation and rates of evaporation and precipitation (water budget)precipitation (water budget)

– 35 parts per thousand (ppt)35 parts per thousand (ppt)– 35 g/kg35 g/kg

•SalinitySalinity

Constituents of Sea WaterConstituents of Sea Water

•Most abundant seawater elements are sodium (NaMost abundant seawater elements are sodium (Na++) + chloride (Cl) + chloride (Cl--))

• Minor and trace elements also presentMinor and trace elements also present

• Major constituents: SOMajor constituents: SO442-2-, Mg, Mg2+2+, Ca, Ca2+2+, K, K++, and HCO, and HCO33

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Salts in the OceanSalts in the OceanWhy is the ocean salty?Why is the ocean salty?

– Salts going in = salts going outSalts going in = salts going out

• Salts come from:Salts come from:

– River dischargeRiver discharge

– Volcanic eruptionsVolcanic eruptions

• Why is the ocean not Why is the ocean not getting saltier?getting saltier?

Salts Going OutSalts Going Out

• Sea SraSea Sra • Sea SpraySea Spray

• BiologicalBiological– Fecal pelletsFecal pellets– Shell formationShell formation

• Mid-ocean ridge magmaMid-ocean ridge magma

• EvaporitesEvaporites

• AdsorptionAdsorption

Factors Affecting SalinityFactors Affecting Salinity

•PrecipitationPrecipitation

• EvaporationEvaporation

• River runoffRiver runoff

• FreezingFreezing

Principle of Constant Principle of Constant ProportionsProportions

– Because of this principle, it is Because of this principle, it is necessary to test for 1 salt ion necessary to test for 1 salt ion (usually Cl) to determine total (usually Cl) to determine total amount of salt presentamount of salt present

– The amount of salt varies, but the The amount of salt varies, but the relative proportions of ions are constantrelative proportions of ions are constant

Determining SalinityDetermining Salinity

1.1. Calculating Salinity Calculating Salinity

– Salinity=1.8065 x chlorinity (Salinity=1.8065 x chlorinity (‰)‰)

2.2. Salinometers Salinometers

– Salinity determined by the Salinity determined by the electrical conductivity electrical conductivity produced by dissolved saltsproduced by dissolved salts

Oceans IIOceans II

Surface CurrentsSurface Currents

Heat VariationsHeat VariationsLatitudeLatitude

• Depends on angle sunlight hits surfaceDepends on angle sunlight hits surface

– At equator, sunlight covers less area; more At equator, sunlight covers less area; more heat heat

– Sunlight at polar latitudes covers wider area; therefore, Sunlight at polar latitudes covers wider area; therefore, less heatless heat

Heat TransferHeat Transfer

• Heat is transferred from equator to polesHeat is transferred from equator to poles– Air CirculationAir Circulation– Ocean currentsOcean currents

Origin of CurrentsOrigin of Currents

•Ocean surface currents are wind drivenOcean surface currents are wind driven

• Air movement due to Air movement due to less denseless dense air rising and air rising and more more densedense air sinking air sinking

• Horizontal air flow along Earth’s surface is Horizontal air flow along Earth’s surface is windwind• Air circulating in this manner is Air circulating in this manner is convection currentsconvection currents

Wind MovementWind MovementNon-rotating EarthNon-rotating Earth

•Simple wind patternSimple wind pattern– Warm air rises at equator, flows toward polesWarm air rises at equator, flows toward poles– Air cools at poles, sinks, and flows toward equatorAir cools at poles, sinks, and flows toward equator

• Winds named by direction Winds named by direction fromfrom which they blow which they blow– North-blowing winds = southerly windsNorth-blowing winds = southerly winds– South-blowing winds = northerly windsSouth-blowing winds = northerly winds

Wind MovementWind MovementRotating EarthRotating Earth

•At equator, warm air risesAt equator, warm air rises– Zone of low pressureZone of low pressure

– Clouds and precipitationClouds and precipitation

– Reaches troposphere Reaches troposphere and moves polewardand moves poleward

– As it spreads, it As it spreads, it coolscools• 3030° N&S, cool air sinks° N&S, cool air sinks

– Area of high pressureArea of high pressure

– Dry conditionsDry conditions

– Location of world desertsLocation of world deserts

• 60° N&S, air masses meet60° N&S, air masses meet– Form Form Polar FrontPolar Front– Air masses rise, diverge Air masses rise, diverge

and sink @ 90° and 30° and sink @ 90° and 30° N&SN&S

Wind MovementWind Movement

• Air that sinks does not flow back in a straight north-south Air that sinks does not flow back in a straight north-south path – it curves (Coriolis Effect)path – it curves (Coriolis Effect)

• At equator, warm air rises, condenses and precipitatesAt equator, warm air rises, condenses and precipitates

• At 30° and 90°, cool air sinksAt 30° and 90°, cool air sinks

Rotation on a GlobeRotation on a Globe

• Buffalo and Quito located on same line of Buffalo and Quito located on same line of longitude longitude (79ºW)(79ºW) • Both cities circles the globe in one day (360Both cities circles the globe in one day (360º/º/24 hours = 1524 hours = 15º/1 hour)º/1 hour)• Quito has larger circumference; thus, travels fartherQuito has larger circumference; thus, travels farther

• Quito needs to travel faster than BuffaloQuito needs to travel faster than Buffalo

Apparent DeflectionApparent Deflection• Hypothetical war gameHypothetical war game

• If a cannonball is shot If a cannonball is shot north from Quitonorth from Quito

• It will travel a straight pathIt will travel a straight path

• But, because Earth is But, because Earth is rotating east to westrotating east to west

• The cannonball appears The cannonball appears to veer to the right in to veer to the right in Northern HemisphereNorthern Hemisphere

• This is the Coriolis EffectThis is the Coriolis Effect

Wind MovementWind MovementCoriolis EffectCoriolis Effect

•Deflected winds due to Deflected winds due to movement over spinning movement over spinning objectobject

• In Northern Hemisphere:In Northern Hemisphere:

• In Southern Hemisphere:In Southern Hemisphere:

– Winds are deflected to the rightWinds are deflected to the right

– Travel clockwise around high PTravel clockwise around high P

– Winds are deflected to the leftWinds are deflected to the left

– Travel counter-clockwise Travel counter-clockwise around high Paround high P

– Produce wind bandsProduce wind bands

Assume water-covered Earth

Surface Current CirculationSurface Current Circulation