Unit 6 - Thermohaline circulation

Question 1

Thermohaline circulation:

Answer 1

Circulation pattern that connects major surface and deep water currents

Question 2

Reasons why density of water increases at high latitudes

Answer 2

Winds:

• Cold winds blowing over the oceans chill surface water beneath them, increasing density.
• Winds increase evaporation, leaving behind saltier water, therefore increasing density.

Sea ice formation:
- As sea ice is formed, salt is forced out into the water below the ice. This increases the salinity of the cold water below the ice, increasing density.

Question 3

Role of temperature in formation of Thermohaline current

Answer 3

Thermohaline current is drivern by the circulation of water at the poles. This circulation is achieved through the sinking and rising of water, which is determined by the density of the water. Cold water is denser than warm water, because the water particles slow down and come closer together, increasing the mass per volume of the water, i.e density. Denser cold waters sink below the warmer waters. As these waters radiate heat, they become cooler, and sink below warmer waters. This creates a circulation that drives the thermohaline current.

Question 4

Role of Salinity in formation of the Thermohaline current

Answer 4

Salinity is the amount of salt per volume of water. Evaporation at the poles due to wind vcauses excess salt to be left behind, increasing salinity., The formation of the ice-caps is also another factor. As they form, salt is pushed out of the ice crystals, which means the water below the ice-caps have increased salinity. Increased salinity means there is more mass occupying each volume of water. This will mean an increase in density, which drives the circulation of water therefore the thermohaline current.