Examine the reasons for horizontal variation of salinity.

The following are the reasons for horizontal variation of salinity in oceans :

1. Evaporation and precipitation : Where evaporation is high the salinity will be high in hot and dry regions. If somewhere rainfall is high the salinity will be low. Example, equatorial regions.

2. Fresh Water : If the source of fresh water is regular, the surface salinity will be low. Polar regions have the low salinity by the process of freezing and thawing of ice.

3. Wind is another factor responsible for the movement of water from one area to another also influences salinity.

4. The ocean currents which are moving laterally or vertically in different parts of the ocean contribute to the salinity variations.