Which of the following statements are correct about sea water. (A) The density of sea water depends upon temperature, pressure and salinity (B) Convergence of water has no effect on density (C) The thermal expansion of water varies with the increase and decrease of temperature (D) In the middle latitudes, due to an excess of precipitation the density is higher Choose the correct answer from the options given below:

Which of the following statements are correct about sea water. (A) The density of sea water depends upon temperature, pressure and salinity (B) Convergence of water has no effect on density (C) The thermal expansion of water varies with the increase and decrease of temperature (D) In the middle latitudes, due to an excess of precipitation the density is higher Choose the correct answer from the options given below: Correct Answer (A) and (C) only

Correct Answer: (A) and (C) only.

Key Points

• The density of seawater depends on temperature and salinity.
• Higher temperatures decrease the density of seawater, while higher salinity increases the density of seawater. 
• Density is directly proportional to pressure and indirectly proportional to temperature.
• As pressure increases, with temperature constant, density increases.
• Conversely when temperature increases, with pressure constant, density decreases.
• Temperature and density share an inverse relationship.
• As temperature increases, the space between water molecules increases—also known as density, which therefore decreases.
• If the temperature of water decreases its density increases, but only to a point.
• Thermal expansion is caused when seawater expands because of the higher temperature of the water.
• Since the oceans absorb heat from the atmosphere when the atmosphere becomes warmer so will the oceans.
• The two major causes of global sea-level rise are thermal expansion caused by warming of the ocean (since water expands as it warms) and increased melting of land-based ice, such as glaciers and ice sheets.
• Pressure is another factor that affects density. Pressure increases with depth; this can be felt when a swimmer goes underwater and has to relieve ear pressure at certain levels. As pressure increases with depth, so does the density of a water mass. Because high-density water sinks and low-density seawater rises, this distinct change in density generates water motion. This concept is extremely important in the world's oceans because it is a chief mechanism controlling the movement of major currents and ocean circulation patterns.​

Additional Information

• Oceanographers and climatologists are interested in the distributions of both temperature and salinity in the world's oceans because they are two factors that determine vertical thermohaline circulation. 
• Thermohaline comes from two words: Thermo for heat and haline for salt. Of the three factors—temperature, salinity, and pressure—that have an effect on water density, temperature changes have the greatest effect.