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?

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

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

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

   • Rain shifts east
   • Less upwelling off South America and warmer eastern Pacific water
   • 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 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 120 m
   • About 4,500 m
7. 5.

   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
8. 6.

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

   • Upwelling brings up more cold water
   • The trade winds grow stronger
   • Upwelling brings up less cold, deep water
   • Sea ice melts nearby
9. 7.

   A number line of anomalies above and below zero. 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?

   • 2.4 °C above normal
   • 0.8 °C above normal
   • 1.2 °C above normal
   • 0.8 °C below 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 29 °C
    • About 21 °C
    • About 3.6 °C
    • About 37 °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 drops, with about 60% fewer hurricane days
    • It doubles
    • It does not change
    • It rises sharply
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 20
    • About 80
    • About 30