Factors affecting salinity
Topic: Oceans: Hydrological Cycle, Relief of the Ocean Floor, Temperature and Salinity · NCERT: Class 11, Ch 12 "Water (Oceans)"
Meaning
Salinity is the amount of salt dissolved in seawater. It changes when fresh water is added to or taken from the sea:
- Evaporation removes water and leaves salt behind, so it raises salinity. Rain lowers it.
- River water lowers salinity along coasts.
- In polar seas, freezing raises salinity, because ice leaves its salt in the water around it. Melting ice lowers it.
- Winds and ocean currents carry saltier or fresher water from place to place.
Salinity, temperature and density are linked, because together they decide whether water sinks or floats.
Example
The Red Sea, between Africa and the Arabian Peninsula, reaches up to 41‰. It is nearly landlocked, evaporation is intense, almost no rivers flow in and rain is rare.
Don't confuse with
- Factors affecting ocean temperature: those are latitude, land and water, winds and currents. Salinity depends mainly on how much fresh water is gained or lost.