Download Unit 10 Lesson 5

Unit 10 Lesson 5 Ocean Currents
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Unit 10 Lesson 5 Ocean Currents
Florida Benchmark
• SC.6.E.7.3 Describe how global patterns such as
the jet stream and ocean currents influence local
weather in measureable terms such as
temperature, air pressure, wind direction and
speed, and humidity and precipitation.
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Remember the essential question…
o By the end of this lesson, you should be able to
describe the movement of ocean water, and explain
what factors influence this movement, and explain
why ocean circulation is important in the Earth system.
Unit 10 Lesson 5 Ocean Currents
Going with the Flow
What are ocean currents?
 Ocean currents are streamlike movements of
water in the ocean.
 Surface currents are ocean currents that occur
at or near the surface of the ocean.
• The Gulf Stream is a surface current.
 The sequence that produces movement of
ocean water is the sun->wind in the atmosphere->surface
currents in the ocean
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Unit 10 Lesson 5 Ocean Currents
What affects surface currents?
 Surface currents are affected by continental
deflections, the Coriolis effect, and global winds.
• When surface currents meet continents, they are
deflected and change direction.
 The deflection of moving objects from a straight
path due to Earth’s rotation is the Coriolis
effect.
 If Earth did not have continents surface currents would travel
in regularly shaped curves
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Unit 10 Lesson 5 Ocean Currents
What affects surface currents?
• In the Northern Hemisphere, currents are deflected to
the right.
• In the Southern Hemisphere, currents are deflected to
the left. Therefore, they flow in a counterclockwise
direction.
• Global winds can push ocean water across Earth’s
surface to create surface currents.
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Unit 10 Lesson 5 Ocean Currents
What powers surface currents?
• The major source of energy that powers surface
currents is the sun.
• The sun causes differences in temperature across
Earth, which causes differences in air pressure.
• Winds form as a result of differences in air
pressure and create surface currents.
 The role that heat plays in the formation of
convection currents is when water loses heat, it
becomes denser and sinks
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Unit 10 Lesson 5 Ocean Currents
Current Events
How do deep currents form?
 Deep currents are movements of ocean water
below the surface caused by differences in density.
• Density is the amount of matter in a given space or
volume.
 Salinity and temperature of water are the two
factors that are responsible for the formation of
deep currents.
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Unit 10 Lesson 5 Ocean Currents
How do deep currents form?
• Salinity is a measure of the amount of dissolved
salts or solids in a liquid.
• Higher salinity makes water more dense.
• Dense water sinks and can form deep water
currents that flow along the ocean floor or on
another layer of denser water.
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Unit 10 Lesson 5 Ocean Currents
What are convection currents?
 Convection currents in the ocean are the
movement of water that results from density
differences.
• Convection currents can be vertical, circular, or
cyclical.
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Unit 10 Lesson 5 Ocean Currents
How do convection currents transfer
energy?
• Water at the ocean’s surface absorbs energy from
the sun, which can be carried to colder regions.
• As water reaches a colder region, it cools and
sinks.
• As warm water moves away, cold water can rise
from the bottom of the ocean, and the cycle
continues.
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