Let’s go step by step to fill in each section of the worksheet comparing El Niño and La Niña. We’ll use simple, clear facts that are easy to remember.
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1. Ocean Temperature Anomalies
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El Niño: The ocean water in the central and eastern Pacific becomes warmer than usual.
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La Niña: The ocean water in the same area becomes cooler than usual.
→ So we write:
*El Niño: Warmer-than-normal sea surface temperatures in the central/eastern Pacific.*
*La Niña: Cooler-than-normal sea surface temperatures in the central/eastern Pacific.*
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2. Frequency and Duration
- Both happen every 2 to 7 years (not on a fixed schedule).
- Each event usually lasts about 9 to 12 months — sometimes longer.
→ So we write:
*Both occur every 2–7 years. Each typically lasts 9–12 months, but can last up to 2 years.*
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3. Atmospheric Effects
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El Niño: Weakens trade winds (winds that blow from east to west across the Pacific). This lets warm water slosh back toward South America.
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La Niña: Strengthens trade winds. Pushes warm water farther west, letting cold water rise near South America.
→ So we write:
*El Niño: Weaker trade winds; less upwelling of cold water.*
*La Niña: Stronger trade winds; more upwelling of cold water.*
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4. Global Impacts on Weather
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El Niño: Causes wetter weather in California and Peru, drier conditions in Australia and Indonesia. Can reduce hurricane activity in the Atlantic.
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La Niña: Causes drier weather in California and Peru, wetter conditions in Australia and Indonesia. Often increases Atlantic hurricanes.
→ So we write:
*El Niño: More rain in southern US & Peru; droughts in Australia/Indonesia; fewer Atlantic hurricanes.*
*La Niña: Drier in southern US & Peru; heavier rains in Australia/Indonesia; more Atlantic hurricanes.*
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5. Effect on Marine Ecosystems
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El Niño: Warm water reduces nutrients → fish die or move away → birds and seals starve. Coral reefs may bleach.
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La Niña: Cold, nutrient-rich water comes up → lots of plankton → fish thrive → seabirds and marine animals do well.
→ So we write:
*El Niño: Less food for fish → population drops; coral stress/bleaching.*
*La Niña: More nutrients → boom in fish populations; healthier marine life.*
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Now let’s put it all together neatly for the final answer.
Final Answer:
Ocean Temperature Anomalies
El Niño: Warmer-than-normal sea surface temperatures in the central/eastern Pacific.
La Niña: Cooler-than-normal sea surface temperatures in the central/eastern Pacific.
Frequency and Duration
Both occur every 2–7 years. Each typically lasts 9–12 months, but can last up to 2 years.
Atmospheric Effects
El Niño: Weaker trade winds; less upwelling of cold water.
La Niña: Stronger trade winds; more upwelling of cold water.
Global Impacts on Weather
El Niño: More rain in southern US & Peru; droughts in Australia/Indonesia; fewer Atlantic hurricanes.
La Niña: Drier in southern US & Peru; heavier rains in Australia/Indonesia; more Atlantic hurricanes.
Effect on Marine Ecosystems
El Niño: Less food for fish → population drops; coral stress/bleaching.
La Niña: More nutrients → boom in fish populations; healthier marine life.
Parent Tip: Review the logic above to help your child master the concept of el nino worksheet.
