El Niño and La Niña

• Every few years, air currents in the Pacific weaken or reverse, causing El Niño. Sometimes they get stronger, causing La Niña
• Normal conditions

  • trade winds over pacific go East —> west
  • South America —> Australia and Indonesia
  • winds push warm water to west
  • warm water heats air in the west, causing low pressure in Australia (lots of rainfall)
  • Peru experiences high pressure and little rain
• El Niño:

  • trade winds reverse and blow West —> East
  • Australia + Indonesia —> South America
  • warm water goes to South America, causing low pressure and high rain there
  • Australias’ water is cooler and there is high pressure with dry conditions
  • Australia may experience droughts and wildfires
• La Niña:

  • tends to follow el niño
  • same as a normal year (E—>W) but more extreme
  • Australia may experience flooding
  • Peru has droughts