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

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

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

4. Use this

   Cross-section of the Pacific warm layer.

5. 3.

   NOAA: normally the warm layer is about 150 m thick in the west, while the eastern thermocline is about 30 m deep. How much deeper does the western warm layer reach, by Kira's math?

   • About 4,500 m
   • About 5 m
   • About 180 m
   • About 120 m
6. 4.

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

   • Trade winds pile water up in the west
   • Upwelling raises the water at Peru
   • El Niño pushes it west
   • The Moon's pull, by itself
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
   • Sea ice melts nearby
   • The trade winds grow stronger
   • Upwelling brings up more cold water

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?

   • 0.8 °C above normal
   • 2.4 °C above normal
   • 1.2 °C above normal
   • 0.8 °C below 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?

    • A permanent change
    • La Niña, cooler than normal
    • Neither, since below normal means warmer
    • El Niño, warmer than normal
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 37 °C
    • About 3.6 °C
    • About 29 °C

12. Use this

    Map of the U.S. with the jet stream dipping south or north.

13. 9.

    NOAA: in moderate to strong El Niño years, how does North Atlantic hurricane activity typically change, by Tala's reading?

    • It rises sharply
    • It does not change
    • It drops, with about 60% fewer hurricane days
    • It doubles
14. 10.

    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 20
    • About 110
    • About 80