GEOLOGY

Detailed explanation-1: -Water gets colder with depth because cold, salty ocean water sinks to the bottom of the ocean basins below the less dense warmer water near the surface.

Detailed explanation-2: -Yes, ocean salinity does change with depth. Generally, the less salty water is found on the surface of the ocean and the upper layers while the denser and more salty water is found in deeper depths.

Detailed explanation-3: -When the water molecules of the ocean become heated, they expand. Extra space is created by this expansion into which salt and other molecules (e.g., calcium) can fit. Since warmer water thus can hold more salt and other molecules than cold water; it can have a higher salinity.

Detailed explanation-4: -The salt in the sea water ‘moves together’ with the water. Thus, when warm water flows from the equator to the poles it transports salt to the poles. At the poles water cools down and sinks (together with salt).

Detailed explanation-5: -This mass of water is called Antarctic Bottom Water, which is formed in a few distinct locations around Antarctica, where seawater is cooled by the overlying air and made saltier by ice formation (which leaves the salt behind in the unfrozen water).