9.2.7: Salinity and Latitude
selected template will load here
This action is not available.
Figure 7.24 is a map of the globe comparing the rates of evaporation and precipitation. The map is a compilation of
evaporation minus precipitation (E-P)
values. The data basically shows the regions where there is a net gain of salinity created in surface waters by high evaporation rates. There is also a net loss of salinity where precipitation is higher than evaporation rates (Figure 7.25). In general:
• The
tropics
(equatorial region) is humid and cloudy, and receives much more rain than evaporates.
• The
temperate regions
receive less precipitation, so evaporation dominates.
• The
polar regions
have low evaporation rates relative to the amount of precipitation they receive.
Figure 7.24. Map of net
evaporation minus precipitation (E-P)
on oceans.
Variability of ocean salinity: Ocean salinity is stable at depth but can be highly variable at the surface. The upper surface layers of the ocean impacted by wave energy is a mixing zone. Simply this: the more waves, the more mixing. Freshwater is less dense than seawater and without mixing freshwater will float (stratify) on top of seawater.
|
Factors that decrease salinity
:
|
Factors that increase salinity
:
|
|
•
Precipitation
• Runoff • Melting icebergs/sea ice |
•
Evaporation
• Freezing sea ice |