Oceans: Oceans: Temperature, Composition, Temperature, Composition,

Structure, & Currents Structure, & Currents

Sea Surface TemperatureSea Surface Temperature

Varies from north to south due to the Sun’s radiation

Band of warm water shifts with seasons

Northward – JJA and Southward – DJF

Sea Surface TemperatureSea Surface Temperature• Variations in Incoming Variations in Incoming

Solar Radiation Solar Radiation Intensity of Solar heatingIntensity of Solar heating– Tilt of the Earth Tilt of the Earth – Thickness of atmosphereThickness of atmosphere

• Solar Rays perpendicular Solar Rays perpendicular to Earth’s surface to Earth’s surface Most Intense HeatingMost Intense Heating– EquatorEquator– Tropics of Cancer & CapricornTropics of Cancer & Capricorn

• Solar Rays at lower Solar Rays at lower angles angles Least Intense Least Intense HeatingHeating– Polar regionsPolar regions

Variations in SunVariations in Sun’’s rays with s rays with latitudelatitude

The Ocean is The Ocean is layered:layered:• Surface waterSurface water

– Salty due to Salty due to evaporationevaporation

– Warmer – solar Warmer – solar radiationradiation

• Middle Middle – ColdCold– SaltySalty

• Dense bottom waterDense bottom water– ColdCold

Ocean basins

Temperature variations within Temperature variations within ocean basinsocean basins

Salinity of SeawaterSalinity of Seawater

• Water is polar –Water is polar –– O is (-) and attracted to (+) charged particles O is (-) and attracted to (+) charged particles

CATIONSCATIONS– H are (+) and attracted to (-) charged particles H are (+) and attracted to (-) charged particles

ANIONSANIONS

• The cation sodium attaches to the negative The cation sodium attaches to the negative sideside

• The anion chlorine attaches to the positive The anion chlorine attaches to the positive sideside

• The figure illustrates dissolved saltThe figure illustrates dissolved salt

In 1000 grams of In 1000 grams of seawater…seawater…

Source of salts?Source of salts?Chemical weathering of Chemical weathering of rocks (dissolved load)rocks (dissolved load)

Volcanic activity: Volcanic activity: outgassingoutgassing

Why is the ocean blue?Why is the ocean blue?

• Intensity of water Intensity of water at different depthsat different depths

• Absorptions is Absorptions is greater for longer greater for longer wave lengths-redwave lengths-red

• Ocean is blueOcean is blue• Most of the light is Most of the light is

absorbed in the absorbed in the few meters of few meters of waterwater

Factors that affect Factors that affect SALINITY-SALINITY-

Fig. 16.4, p.402

Precipitation and Precipitation and EvaporationEvaporation

Red-precipitationBlue-evaporation

Density = mass/volumeDensity = mass/volume

• What factors change the density of What factors change the density of sea water?sea water?

As temperatures increase, density decreases

As salinity increases, density increases

Density and Ocean Density and Ocean StructureStructure

Coriolis effect: earthCoriolis effect: earth’’s s rotation causes gyres causes gyres

GyresGyres or circular patterns or circular patterns in the oceans create in the oceans create currentscurrents

The Gulf StreamThe Gulf StreamHow Benjamin Franklin How Benjamin Franklin described it in 1770: described it in 1770: How satellites see it:How satellites see it:

Air Temperature is influenced Air Temperature is influenced by ocean currents.by ocean currents.

Ocean currents influence Ocean currents influence climateclimate

UpwellinUpwellingg

• Wind blows water away Wind blows water away from shorefrom shore

• Cold nutrient-rich water Cold nutrient-rich water is is ““pulledpulled”” to the surface to the surface

• Nutrients are Nutrients are produced by produced by bacterial decay of bacterial decay of materialmaterial

• Phosphates, Phosphates, nitrates, carbonatesnitrates, carbonates

• Provide nutrients Provide nutrients for plankton (base for plankton (base of the food chain)of the food chain)

Upwelling: bottom waters Upwelling: bottom waters are nutrient richare nutrient rich

Upwelling: Upwelling: wherewhere

Upwelling: Upwelling: significancesignificance

• Supplies basic nutrients Supplies basic nutrients for single-celled for single-celled organisms organisms

• Diatoms (plants)Diatoms (plants)

• Offshore IrelandOffshore Ireland

• Coast of CaliforniaCoast of CaliforniaRed: highest concentration