Ocean Currents

Purpose: To identify, describe and list factors that control ocean

currentsTo 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 bottle 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 handcrafted raft 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 rafted 3000 miles across the Pacific Ocean and settled 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 entire oceans

Surface Currents are influenced by:

Global windsThe Coriolis EffectContinental deflections

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-latitudes

Ocean currents distribute heat throughout the depths of the

oceanhttp://topex-www.jpl.nasa.gov/overview/climate-water.html

The Coriolis Effect

Winds, ocean currents and moving objects appear to move in curved paths as the Earth rotates beneath

Coriolis Effect Demonstration:Northern Hemisphere

Draw 2 circles Rotate the paper

counterclockwise Prediction: Draw a straight

line from a to b. Describe the result

Draw a straight line from c to d. Describe the result

a

b

c

d

Coriolis Effect Demonstration:Southern Hemisphere

Draw 2 circles Rotate the paper

clockwise Prediction: Draw a straight

line from a to b. Describe the result

Draw a straight line from c to d. Describe the resultc

d

a

b

Continents cause surface currents to change directions

Surface currents affect climates of the world

The Gulf Stream brings warm water from the Equator to northern Europe

Warmer climates result in latitudes 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 location 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 patterns 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 patterns 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, creating hazardous driving conditions

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 Institute are stationed in the Pacific Ocean to monitor water temperature

and El Nino events

El Nino will be back

What do you know?A supertanker breaks apart off the coast of Japan.

Millions of gallons of crude oil spill into the ocean.

Prepare a news broadcast detailing how San

Diego’s beaches could be affected. Draw a map and use your notes to explain your answer.

San Diego