Tag: oceans : temperature, salinity and density

The movement of ocean waters or ocean currents takes place due to the effect of earth's rotation, wind difference, salinity and density of seawater, etc. The current in the ocean is originated due to the combined effect of all these factors acting internally as well as externally. 

After 2000m, the temperature of the seawater is uniform everywhere. It is around $4 ^oC$ according to depth. And therefore, the water of greater depths does not freeze.

Temperate is one of the major property of seawater. It always varies from region to region. The surface temperature of the sea water decreases from the equatorial area towards the poles.

In mid-latitudinal zones, rainfall is less and the supply of freshwater from various rivers is also low. This zone has the hot deserts of the world. 

In seas where the supply of freshwater exceeds the rate of evaporation, salinity is low. Near the estuaries generally the salinity is low because ample amount of fresh water enters the sea or ocean.

Because of the sun's heat, evaporation happens at a faster rate. Evaporated water turns into water vapour and reduces in quantity. But amount of salt remains the same in the remaining water and therefore the salinity of the water increases.

The uneven distribution of temperature on earth, uneven supply of freshwater, etc. affects the salinity of seawater. If temperature is high, evaporation will be high and it will result in high salinity. Again if evaporation is high but supply of fresh water exceeds evaporation than salinity will be low. So in many ways the salinity of sea water is effected.

Salinity is the amount of salt dissolved in a body of water. Salinity is an important factor in determining many aspects of the natural waters and of biological process within it, and is a thermodynamic state variable that, along with temperature and pressure, governs physical characteristics like the density and heat capacity of the water.

Temperature and salinity are the two properties of sea water that control the density of the sea water. If temperature reduces, density of water increases.