If the salinity of ocean waters is
analyzed, it is found to vary only slightly from place to place.
Nevertheless, some of these small changes are important. There are three
basic processes that cause a change in oceanic salinity.
One of these is the subtraction of water from the ocean by means of evaporation - conversion of liquid water to water vapor. In this manner the salinity is increased, since the salts stay behind. If this is carried to the extreme, of course, white crystals of salt would be left behind.
The opposite of evaporation is precipitation, such as rain, by which water is added to the ocean. Here the ocean is being diluted so that the salinity is decreased. This may occur in
areas of high rainfall or in
coastal regions where rivers flow into the ocean. Thus salinity may be
increased by the subtraction of water by evaporation, or decreased by
the addition of fresh water by precipitation or runoff.One of these is the subtraction of water from the ocean by means of evaporation - conversion of liquid water to water vapor. In this manner the salinity is increased, since the salts stay behind. If this is carried to the extreme, of course, white crystals of salt would be left behind.
The opposite of evaporation is precipitation, such as rain, by which water is added to the ocean. Here the ocean is being diluted so that the salinity is decreased. This may occur in
Normally, in tropical regions where the sun is very strong, the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation. Similarly, in coastal regions where rivers dilute the sea, salinity is somewhat lower than in other oceanic areas.
A third process by which salinity may be altered is associated with the
formation and melting of sea ice. When sea water is frozen, the
dissolved materials are left behind. In this manner, sea water directly
beneath freshly formed sea ice has a higher salinity than it did before
the ice appeared. Of course, when this ice melts, it will tend to
decrease the salinity of the surrounding water. In the Weddell Sea
Antarctica, the densest water in the oceans is formed as a result of
this freezing process, which increases the salinity of cold water. This
heavy water sinks and is found in the deeper portions of the oceans of
the world.
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