Lesson 6 Development of Ocean Currents Sci 20F

S2-4-03 Explain effects of heat transfer within the atmosphere and hydrosphere on the development and movement of wind and ocean currents.Include: Coriolis effect/convection, prevailing westerlies, jet streams, El Nino

Read Science Power 10 p. 469 – 480 (Ocean Currents):

How do oceans respond to the prevailing winds?

Surface Currents

Started by surface winds Like giant rivers in the seas – called ocean currents Carry warm waters from the equator to the Arctic Sea Blocked and diverted by continents (unlike wind currents) Affected by the Coriolis effect (just like wind currents)

o Currents turn to the right in the Northern Hemisphereo Currents turn to the left in the Southern Hemisphere

Warm currents are faster than cold currents

Deep Currents

Ocean currents that are deeper than 100 m Not affected by winds Slow moving Can also move vertically

Lab Activity: p. 472 – 473 Moving Mountains of Water

El Nino video (4.5 min): https://www.youtube.com/watch?v=WPA-KpldDVc

Upwelling

Normally, cold water sinks in warmer water because it is more dense Cool water can rise though in a process called upwelling When cool water comes up to replace warmer water that has been blown

away by constant wind Upwelling brings rich nutrients up from the ocean floor Causes algae to thrive, fish feed on this algae Results in excellent fishing

El Nino

See diagram on p. 476 of Science Power 10 textbook on next page A warming of eastern Pacific waters off the coast of South America Occurs every few years Caused by a reversal of the direction of the trade winds between South

America and Australia and Indonesia Affects weather throughout the world Example: Causes droughts in Australia and Ethiopia, but brings storms and

flooding to California The opposite of El Nino is La Nina

Ocean Currents: Check Your Understanding

1. Name 3 factors that determine the speed and direction of surface currents in oceans?Surface wind/Prevailing wind, continents (land mass and shoreline shape), & Coriolis effect

2. Describe 2 ways that ocean currents can influence the climate of coastal regions.

Ocean currents bring water of a different temperature close to land. It depends on the temperature of the water relative to the air. By cooling the air, this cool air cannot hold as much water vapour as warm air. So when it moves ashore, there will be very few clouds and not much rain. But if it warms the air, there will be an increase in precipitation.

3. What can cause the salt concentration of sea water to change (could be an increase or decrease)?

Increase: Ocean water freezing into ice or lots of evaporation (this removes almost completely fresh water, leaving salt behind)

Decrease: An increase in fresh water (ex. Hurricane, melting iceberg, near a large river delta)

4. Under what conditions will cool water rise?

Winds push the warmer surface water away, causing cold air to rise (upwelling)

Also rises if it enters a region of denser water (cooler or saltier), or if a physical barrier, such as a continental shelf, forces it up.

5. Describe two events that occur while an El Nino is developing.

Trade winds diminish and reverse (winds start blowing east instead of west)

Pushes the bulge of warm water normally present in the western Pacific to the east (near Peru, away from Australia), upwelling occurs in the west

6. How do conditions in Peru change when an El Nino is developing?

Water gets warmer, fishing gets worse, flooding and excessive rain

7. What is it called when the opposite factors that create El Nino, occur?

La Nina

Lesson 6 Development of Ocean Currents Sci 20F

S2-4-03 Explain effects of heat transfer within the atmosphere and hydrosphere on the development and movement of wind and ocean currents.Include: Coriolis effect/convection, prevailing westerlies, jet streams, El Nino

Read Science Power 10 p. 469 – 480 (Ocean Currents):

How do oceans respond to the prevailing winds?

Surface Currents

Started by _____________ _______ _____ Like giant ___________ in the seas – called ___________ ______________ Carry ___________ waters from the equator to the Arctic Sea Blocked and diverted by ______________ (unlike ___________ currents) Affected by the ______________ effect (just like ____________ currents)

o Currents turn to the __________ in the Northern Hemisphereo Currents turn to the __________ in the Southern Hemisphere

______________ currents are faster than _____________ currents

Deep Currents

Ocean currents that are deeper than ______ m Not affected by __________ ______________ moving Can also move ______________

Lab Activity: p. 472 – 473 Moving Mountains of Water

El Nino video (4.5 min): https://www.youtube.com/watch?v=WPA-KpldDVc

Upwelling

Normally, cold water ___________ in warmer water because it is more ______________

Cool water can rise though in a process called ________________ When cool water comes up to replace warmer water that has been

____________ ___________ by constant wind Upwelling brings rich ________________ up from the ocean floor Causes ____________ to thrive, ________ feed on this algae Results in excellent _______________

El Nino

See diagram on p. 476 of Science Power 10 textbook on next page A ______________ of eastern Pacific waters off the coast of South America Occurs every few __________ Caused by a ______________ of the direction of the trade winds between

South America and Australia and Indonesia Affects weather throughout the ___________ Example: Causes droughts in Australia and Ethiopia, but brings storms and

flooding to California The opposite of El Nino is _____________

Ocean Currents: Check Your Understanding

1. Name 3 factors that determine the speed and direction of surface currents in oceans?

2. Describe 2 ways that ocean currents can influence the climate of coastal regions.

3. What can cause the salt concentration of sea water to change?

4. Under what conditions will cool water rise?

5. Describe two events that occur while an El Nino is developing.

6. How do conditions in Peru change when an El Nino is developing?

7. What is it called when the opposite factors that create El Nino, occur?