El Niño and La Niña

Grade 9 Science Worksheet

Circle the best answer.

1. Read this first

   Use this

   Trade-wind arrows of different lengths across the Pacific.

2. 1.

   NOAA: normally air pressure is lower at Darwin and higher at Tahiti. What changes during El Niño, by Bo's reading?

   • Pressure stops mattering
   • Pressure at Tahiti rises even higher than it already is
   • Both pressures become equal for good
   • Pressure at Darwin becomes higher than at Tahiti
3. 2.

   Why does warm water normally pile up in the western Pacific, by Esme's reading (NOAA)?

   • Rivers in Asia add it
   • Upwelling brings it up
   • Trade winds push water east
   • Trade winds push surface water west
4. 3.

   Cold water rising off South America, with arrows of different sizes. During La Niña, trade winds are stronger than normal. What follows, by Jun's reading (NOAA)?

   • Less upwelling off South America and warmer eastern Pacific water
   • Rain shifts east
   • Warm water moves back east
   • More upwelling off South America and cooler eastern water

5. Use this

   Cross-section of the Pacific warm layer.

6. 4.

   NOAA: normally sea level is about 46 cm higher near Indonesia than near Peru. What causes this, by Luz's reading?

   • El Niño pushes it west
   • Upwelling raises the water at Peru
   • The Moon's pull, by itself
   • Trade winds pile water up in the west
7. 5.

   During El Niño the eastern thermocline deepens. Why does the surface water there warm, by Milo's reading (NOAA)?

   • Upwelling brings up less cold, deep water
   • Upwelling brings up more cold water
   • Sea ice melts nearby
   • The trade winds grow stronger

8. Use this

   A number line of anomalies above and below zero.

9. 6.

   Model data: Niño 3.4 temperatures run 0.4, 0.8 and 1.2 °C above normal over three months. What is the average, by Noah's math?

   • 1.2 °C above normal
   • 0.8 °C below normal
   • 0.8 °C above normal
   • 2.4 °C above normal
10. 7.

    Model data: Niño 3.4 averages 1.0 °C below normal for three months. Which phase does that suggest, by Pia's reading?

    • El Niño, warmer than normal
    • La Niña, cooler than normal
    • Neither, since below normal means warmer
    • A permanent change
11. 8.

    NOAA: western Pacific surface water is normally about 8 °C warmer than off South America. If the west is 29 °C (model), about what is the east, by Ren's math?

    • About 21 °C
    • About 29 °C
    • About 3.6 °C
    • About 37 °C
12. 9.

    Cold water rising off South America, with arrows of different sizes. NOAA: why is there less phytoplankton off South America during El Niño, by Zee's reading?

    • Stronger upwelling brings too many nutrients
    • Weaker upwelling brings up fewer nutrients
    • Trade winds blow them away
    • Colder water stops their growth
13. 10.

    Map of the U.S. with the jet stream dipping south or north. If a normal season had 50 hurricane days (model), about how many would a strong El Niño year have, with NOAA's 60% reduction, by Ari's math?

    • About 30
    • About 110
    • About 20
    • About 80