20.1 Ocean Water Properties

(physical….)(…and chemical.)

Composition of Ocean water

• 96.5% pure water

• Dissolved solids (salts)- Cl , Na, Mg, S, Ca, K- mostly from river runoff

• Dissolved gases-N2, O2, CO2

- From river runoff, atmosphere and undersea volcanoes

- Polar areas have more dissolved gas than tropical areas

Salinity

The amount of dissolved solids in a liquid

Measured in parts per thousand; # of grams of the solid in 1 kg of H2O

Ocean water is 35 parts per thousand salt or 3.5% salt

Factors Affecting SalinityFreezing Increases Water freezes leaving salt

behindPrecipitation Decreases Dilutes surface water

(Tropics)

Evaporation Increase Water evaporates leaving salt behind (Equator)

River Runoff Decrease Dilutes surface water

Depth Increase Evaporation at surface makes in salty at top and less as you go deeper

The RED SEA

The BALTIC SEA!

Hot…High evap rate… SALTY!!

Cool…low evap rate, lots of runoff… NOT SALTY!!

Verses

OCEAN WATER TEMPERATURE

* the IR rays of the SUN heat the ocean waters.* the mixing effect distributes the solar heat down to 300 m.

Tropics surface temp @ 30o CPolar surface temps @ -2o C(pack ice

forms…)Middle lattitudes, surface temps vary

Thermocline

• Zone of rapid temp. change

• Caused by warm/cold barrier

• Waters can’t mix due to differences in density

Density

Affected by salinity and temperature

Cold = more dense

Warm = less dense

Densest water in polar regions

Color

• Ocean water appears blue because only blue light is reflected. The other colors are absorbed.

• Appears blue down to 100m.

• If you go deeper it is black