Ocean Currents Purpose:
To iden3fy, describe and list factors that control ocean currents
To explain how ocean currents affect climate in San Diego and the world
Warm-‐up
© Imagine you are stranded on a desert island in the North Pacific Ocean. You stuff a distress “help” message in a boHle and throw it in the ocean, hoping someone in San Diego will get it.
© Is it possible someone in San Diego will find your message and send help? Explain your answer.
Thor Heyerdahl and crew of 5
© Sailed across the South Pacific from South America in a handcraNed raN called the Kon-‐Tiki in 1947 and landed in Polynesia
© Demonstrated it is possible to travel across the ocean using ocean currents and wind
© Believed people from Peru raNed 3000 miles across the Pacific Ocean and seHled the islands of Polynesia
Surface Currents
© Are stream like movements of water at the ocean’s surface. They are caused by the prevailing winds
© Circulate thousands of miles across en3re oceans
Surface Currents are influenced by:
© Global winds © The Coriolis Effect © Con3nental deflec3ons
Surface winds (purple arrows) create surface currents (red)
© The Trade Winds move currents east to west along the Equator
© The Westerlies move currents west to east in mid-‐la3tudes
Ocean currents distribute heat throughout the depths of the
ocean
The Coriolis Effect
© Winds, ocean currents and moving objects appear to move in curved paths as the Earth rotates beneath
Coriolis Effect Demonstra3on: Northern Hemisphere
© Draw 2 circles © Rotate the paper
counterclockwise © Predic3on: © Draw a straight line
from a to b. Describe the result
© Draw a straight line from c to d. Describe the result
a
b
cd
Con3nents cause surface currents to change direc3ons
Surface currents affect climates of the world
© The Gulf Stream brings warm water from the Equator to northern Europe
© Warmer climates result in la3tudes that are similar to Canada
© Cold water from the north is carried southward by the California Current
© The cold water current keeps the climate comfortable along the West Coast all year
El Nino:
© is the change in the loca3on of warm and cold surface water every 2-‐7 years
© results in worldwide weather changes © causes heavy rains and mudslides in California and
droughts in other regions
Normal weather paHerns occur when warmer water is found in the western pacific near Asia
During El Nino, purple shows warmer water located near
America in the eastern pacific.
Weather paHerns across the USA and the world are changed
During El Nino years, the Trade Winds weaken and do not
move warm water across the Pacific
Storms develop in the middle of the Pacific bringing heavy winter rain to San Diego
During El Nino, normally wet regions experience drought
and wildfires
Other areas, like S. California experience intense wave damage from storms
Roads are destroyed and cliffs are eroded by waves and
flooding
Homes are flooded. Diseases spread by contaminated water.
Accidents and injuries are greater with stormy weather
Dry riverbeds in Arizona flood, damaging homes in Arizona
Saturated hills slide, crea3ng hazardous driving condi3ons
Mudslides in on steep slopes destroy homes.
Strong winds of El Nino knock down trees
Ocean pier in S. California
Buoys from San Diego’s Scripp’s Ins3tute are sta3oned in the Pacific Ocean to monitor water temperature
and El Nino events
El Nino will be back