Salinity

🎯 How This Word Works in UPSC Writing

The total concentration of dissolved salts in water. Four controls set it: evaporation raises salinity, precipitation and river inflow lower it, the freezing of seawater raises it because salt is excluded from ice, and melting lowers it. The global pattern follows directly, with maxima in the subtropical high-pressure belts where evaporation is intense and rainfall scant, and minima at the equator and in polar waters. Enclosed seas exaggerate whichever factor dominates, which is why the Red Sea is among the most saline and the Baltic among the least. For India the examinable contrast is between the two flanking seas: the Bay of Bengal is markedly less saline than the Arabian Sea because it receives enormous river discharge from the Ganga and Brahmaputra along with heavy rainfall, whereas the Arabian Sea has high evaporation and little inflow. That freshwater cap stratifies the Bay, helping keep its surface warm and favouring cyclone formation.