bellringer make sure you record today’s date, the question and your answer. if there were no land...
TRANSCRIPT
BellringerMake sure you record today’s date, the question and your answer.
If there were no land on Earth’s surface, what would the pattern of surface currents look like? Explain your answer.
Objectives:• Describe surface currents.
• List the three factors that control
surface currents.
• Describe deep currents.
• Identify the three factors that form
deep currents.
Introduction• Ocean current- ocean water that contains
streamlike movements of water.
• Ocean currents are influenced by a number
of factors: weather, Earth’s rotation &
position of continents.
• With knowledge of currents, we can make
predictions of where objects will float.
One Way to Explore Currents• Thor Heyerdahl’s Journey: Thor
Heyerdahl’s completed a long ocean
journey to prove his theory that
ocean currents carried the ancient
Peruvians across the Pacific to
Polynesia.
Surface Currents• Surface current- a horizontal movement of
ocean water that is caused by wind and that
occurs at or near the ocean’s surface.
Example: Gulf Stream
• Controlled by:
• Global Winds
• Coriolis Effect
• Continental Deflection
Global Winds• Different winds cause surface currents
to flow in different directions.
• In much the same way that you create
ripples, winds that blow across Earth’s
surface create surface currents in the
ocean
• Near the equator winds blow east to
west and near the poles it is west to
east
The Coriolis Effect• The Earth’s rotation causes wind
and surface currents to move in
curved paths rather than in straight
lines.
• It causes surface currents in the
Northern Hemisphere to turn
clockwise, and in the Southern
Hemisphere to turn
counterclockwise.
Continental Deflection• When surface currents meet
continents, the currents deflect, or
change direction.
Deep Currents• Deep Ocean Currents- streamlike
movements of ocean water located
far below the surface are called
deep currents.
• Factors that form Deep Ocean
Currents are:
• Temperature
• Salinity
• Density
Formation & Movement of Deep Currents• Deep Ocean Currents- streamlike
movements of ocean water located
far below the surface are called deep
currents.
• Differences in temperature and
salinity— and the resulting
differences in density— cause
variations in the movement of deep
currents. The next slide shows how
deep currents are formed.