EFFECT OF SALINITY ON FREEZING AND DENSITY OF WATER

Figure 6.12

COMPOSITION OF MEAN SEAWATER

EXCESS EVAPORATION INCREASES SALINITY

Figure 6.20

SALINITY OF OCEAN WATER REFLECTS LOSS OF WATER BY EVAPORATION,ICE FORMATION, MELTING, RUNOFF, AND PRECIPITATION

REGIONS OF HIGHER AND LOWER SALINITY

REMEMBER THAT MOW SALINITY =34.9 PPT

Vertical variations of salinity

• Surface ocean salinity is variable

• Deeper ocean salinity is nearly the same (~polar source regions for deeper ocean water)

• Halocline, rapid change of salinity with depth

Figure 6.22SALINITY CHANGE WITH DEPTH

HALOCLINE :

REGION OF RAPID CHANGEOF SALINITY WITH DEPTH

Density of seawater

• 1.022 to 1.030 g/cm3

• Ocean layered according to density

• Density of seawater controlled by temperature, salinity, and pressure– Most important influence is temperature– Density increases with decreasing temperature

• Salinity greatest influence on density in polar oceans( BECAUSE OF CONSTANT TEMPERATURE)

• Pycnocline, rapid change of density with depth

• Thermocline, rapid change of temperature with depth

• Polar ocean is isothermal

Figure 6.24AB

NOTE: TEMPERATURE AND DENSITY REACH A NEAR CONSTANT VALUE AT GREAT DEPTHS IN THE OCEANS

PYCNOCLINE = RAPID CHANGE OF DENSITY WITH DEPTH

THERMOCLINE = RAPID CHANGE OF TEMPERATURE WITH DEPTH

Figure 6.24C

MIXED SURFACE LAYER, MIXED BY WINDS, SURFACE CURRENTS, CORIOLIS EFFECTS

Table 6.5