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Oceans

Oceans. Grade 10 ST. Class Starter Questions. What factors can influence ocean water temperature? Why is ocean water salty? In what parts of the world is the ocean the most salty? How do changes in salinity affect the density of a solution?.

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Oceans

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  1. Oceans Grade 10 ST

  2. Class Starter Questions • What factors can influence ocean water temperature? • Why is ocean water salty? • In what parts of the world is the ocean the most salty? • How do changes in salinity affect the density of a solution?

  3. 1. What factors influence ocean water temperature? • Depth of the water: • surface water is warmed by the sun • the deeper the water, the colder it is. • The seasons • water is colder in winter than in summer • Latitude where body of water is found • water is colder near the poles and warmer near the equator

  4. 1) Depth of the water • Mixed layer • upper warm layer • varies in depth depending on wind, tides and turbulence • Thermocline: • transition zone between warm and cool water • Deep water: • sunlight does not reach this area • very cold

  5. Ocean Temperature Zones

  6. SALINITY A measure of the amount of salt dissolved in a liquid.

  7. 2. Why is ocean water salty? Water in oceans is saline because salts from the lithosphere are dissolved in it.

  8. 3. In what parts of the world is the ocean the most salty? • Near the equator, ocean water has a high salinity because water evaporates due to high temperatures and concentrates the solution. • Near the poles, ice packs and glaciers melt. The fresh water entering the ocean dilutes the salt water, reducing its salinity.

  9. 4) How do changes in salinity affect the density of a solution? • The density of a solution is defined as its mass divided by its volume. d = m/v • When salt is added to water, the mass of the water increases considerably, but its volume only slightly. This results in a higher density. • A solution with less salt dissolved in it will have a lower salinity and also a lower density.

  10. OCEAN CIRCULATION • The water in oceans is in constant movement due to ocean currents, the movement of water in a certain direction. • Ocean circulation is the combination of water movement due to: • surface currents • subsurface currents • rotation of the Earth.

  11. Ocean Currents

  12. SURFACE CURRENTS • caused by wind • move horizontally • carry water as deep as 400 m

  13. SUBSURFACE CURRENTS • Subsurface currents are caused by variations in the density of water. • The density of water is affected by: • the salinity of water • the temperature of the water • Salty and cold water is denser sinks • Less salty and warm water is less dense  rises • These movements create subsurface currents.

  14. Water movement according to density

  15. Thermohaline Circulation • The combination of surface and subsurface currents results in thermohaline circulation. • It functions like a conveyor belt which moves warm and cold water around the Earth. • allows for the transfer of heat around the world, • prevents extremes  cold at the poles and heat around the equator.

  16. Thermohaline Circulation • the Gulf Stream originates near the equator on the Atlantic Coast of Central America and carries warm water up the coast, past Quebec and Labrador.

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