El Niño and La Niña

Grade 9 Science Worksheet

Circle the best answer.

1. 1.

   Trade-wind arrows of different lengths across the Pacific. Why does warm water normally pile up in the western Pacific, by Esme's reading (NOAA)?

   • Rivers in Asia add it
   • Trade winds push surface water west
   • Upwelling brings it up
   • Trade winds push water east
2. 2.

   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)?

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

3. Read this first

   Use this

   Cross-section of the Pacific warm layer.

4. 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 5 m
   • About 180 m
   • About 4,500 m
   • About 120 m
5. 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
   • The Moon's pull, by itself
   • Upwelling raises the water at Peru
   • Trade winds pile water up in the west
6. 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
   • The trade winds grow stronger
   • Upwelling brings up more cold water
   • Sea ice melts nearby

7. Use this

   A number line of anomalies above and below zero.

8. 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
   • 1.2 °C above normal
   • 2.4 °C above normal
   • 0.8 °C below normal
9. 7.

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

   • Neither, since below normal means warmer
   • La Niña, cooler than normal
   • A permanent change
   • El Niño, warmer than normal
10. 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 3.6 °C
    • About 21 °C
    • About 37 °C
    • About 29 °C

11. Use this

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

12. 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 drops, with about 60% fewer hurricane days
    • It doubles
    • It does not change
13. 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 110
    • About 80
    • About 30
    • About 20