Ocean Currents Weather Dynamics Science 20S

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Ocean CurrentsWeather DynamicsScience 20S
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Global Ocean Current Circulation

• What currents can you name?
• Take the online quiz and see what you already
  know about currents
• Click here for the quiz

The Gulf Stream
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What causes ocean currents?

• The earth has 71 of its surface covered by water
• Most of the water is close to the equator and
  much of the land masses are closer to the poles
• Warm water travels from the equator to the poles
  and the reverse is true for cold water (travels
  from the poles to the equator)

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What kinds of things effect currents?

• Convection currents global wind patterns
• Coriolis force shapes of the continents
• Heat capacity of the water salt concentration

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Major global water circulation
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Effects of Ocean Currents

• the coastal areas of some northern countries can
  be warmed by a current which has picked up heat
  at the equator, losing that heat slowly as it
  travels north

• e.g. Norways harbours do not freeze in winter,
  St. Johns Nfld is warmer in winter than Ottawa

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More Effects

• warm air holds more moisture, cold air holds less
• air above a cold current will be dry, helping to
  create desert like conditions on nearby land

• Atacama Desert of Peru

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More Effects

• air above warmer waters will be moist, forming
  clouds and large amounts of precipitation
• (e.g. Brazils rain forests)
• air pressure is also affected by ocean currents
• air above a warm current is less dense, creating
  a low pressure system

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Label the Following
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A completed diagram
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El Niño where does it come from?

• long time-scale events are often associated with
  changes in atmospheric circulations that
  encompass vast areas.
• these persistent circulations occur
  simultaneously over seemingly unrelated parts of
  the hemisphere and result in abnormal weather,
  temperature and rainfall patterns worldwide.
• more on El Niño

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El Niño /Southern Oscillation (ENSO)

• naturally occurring phenomenon
• warming of the ocean water along the equator in
  the Eastern Pacific

El Niño effect (Dec. to Feb.)
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La Niña

• Occurs after El Nino (is usually the reverse)
• the water temperature is lower than normal and is
  called a cold
• Global climate impacts tend to be opposite to
  those of El Niño

La Niña effect (Dec. to Feb.)
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El Nino La Nina
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Links

• Bill Nye The Science Guy (Ocean Currents)