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 6.22 SALINITY CHANGE WITH DEPTH HALOCLINE : REGION OF RAPID CHANGE OF SALINITY WITH DEPTH

Density of seawater to g/cm 3 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