//1.b. Water in the world’s oceans varies horizontally and vertically

Question 1

What is salinity

Answer 1

This is the concentration of sodium chloride. It is expressed a grams of salt per 1000g of water

Question 2

How does salinity vary horizontally and vertically

Answer 2

• fresh water is usually <0.5ppt. The pacific can be 30-35ppt
• salinity varies with depth and becomes lower at the surface (a gradient know as the halocline)
• salinity influences water desnity-this affects movements such as ocean currents which affect climate
• different desnities created affect the vertical movement of water in oceans

Question 3

How does temperature vary horizontally and vertically

Answer 3

• high levels of energy are needed to heat water
• once heated, water retains heat efficiently
• the rise and fall of temperature on land surfaces is much more rapid and this has an impact on weather and climate from global to local scales
• the surface layer varies in depth based on season and location
• at depth, temperature hardly varies

Question 4

What are the two types of ocean currents

Answer 4

Surface currents and deep water currents

Question 5

What are surface currents

Answer 5

• surface cirulation

- these waters make up 10% of all the water in the oceab and form the uper 400m of the ocean

Question 6

What are deep water currents

Answer 6

• thermohaline circulation
• these waters make up the other 90% of the ocean and move around the ocean basins driven by forces of density (a function of salinity and temperature differences)
• ocean currents are influenced by solar heating, winds, gravity and the Coriolis force

Question 7

Explain the process of thermohaline circulation

Answer 7

This is a continuous, slow moving flow of ocean currents around the globe

1) most oceans hold warm water at the surface and cold water in their depths
2) surface water tends to move from low to high latitudes
3) in polar regions, ocean surfaces are cooler, more saline and denser
4) water sinks and moves horizontally
5) deep currents flow back to the equator where water rises

Question 8

How does temperature vary horizontally and vertically-warm currents

Answer 8

• warm currents found at the surface are waem at the equator
• they are cool as they more towards the poles
• warm currents found at the Indian and Pacific ocean

Question 9

How does temperature vary horizontally and vertically-cold currents

Answer 9

• cold currents found at depth are cold at poles
• warm when they rise to the surface at the equator
• colder currents at depth are dound in the Southern and Atlantic ocean

Question 10

The pattern of circulation in the North Atlantic-warm saline water

Answer 10

• warm saline water flows from the coast of Florida in a north easterly direction as the Gulf Stream
• the transfer of heat influences the climate of western Europe
• The North Atlantic Drift in its northern course, this warm current flows up to the Arctic
• as the water cools, its density increases and it sinks
• the water then travels back towards the equator where it will surface 150-250 years later

Question 11

The pattern of circulation in the North Atlantic-Northwest Atlantic

Answer 11

-in the northwest Atlantic, the cold Labrador Current flows south from the Arctic

Question 12

The pattern of circulation in the North Atlantic-warm salty water

Answer 12

• the North Atlantic receives warm, salty water from the Mediterranean via the Straits of Gibraltar
• eventually its desnity matches that of the surrounding water and mixing occurs