Surface ocean currents and the Coriolis effect

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   World map with current arrows. What mainly drives surface ocean currents, by Ari's reading (NOAA)?

   • Rivers flowing into the sea
   • Differences in salt, by themselves
   • Heat from the ocean floor
   • Wind blowing over the water
3. 2.

   About how deep do wind-driven currents reach, by Bo's reading (NOAA)?

   • Down to the sea floor
   • About 10,000 m
   • The upper 100 m or so
   • Just the top 1 cm
4. 3.

   What drives deep-ocean currents instead, by Kira's reading (NOAA)?

   Use the picture in question 2.

   • Surface wind, by itself
   • The engines of ships
   • Differences in density from temperature and salinity
   • The Moon's light
6. 4.

   In the Northern Hemisphere, which way does the Coriolis effect turn moving air and water, by Jun's reading (NOAA)?

   • To the left
   • It does not turn them
   • Straight up
   • To the right
7. 5.

   What causes the Coriolis effect, by Milo's reading (NOAA)?

   Use the picture in question 4.

   • Wind blowing on the water
   • Earth's rotation on its axis
   • Salt in the water
   • The Moon's pull
8. 6.

   Five gyres on a world map with their turning directions. Why are there no gyres at the equator, by Pia's reading (NOAA)?

   • The Coriolis effect is not present there
   • The water is too warm to turn
   • Gyres there turn both ways at once
   • The winds are too strong there
9. 7.

   What is a western boundary current like, by Ren's reading (NOAA)?

   • Weak and broad
   • Tidal, turning twice a day
   • Strong and narrow
   • Deep and cold, driven by salt

10. Read this first

    Use this

    Wind pushing surface water offshore as cold water rises.

11. 8.

    What is upwelling, by Tala's reading (NOAA)?

    • Warm surface water sinking toward the deep ocean
    • Deep, cold water rising toward the surface
    • Waves breaking on the shore
    • Rain filling up the ocean
12. 9.

    Why are fishing grounds often good where upwelling occurs, by Zee's reading (NOAA)?

    • The rising water is warm and nutrient-poor
    • Upwelling pushes the fish to shore
    • Upwelled water is fresh
    • The rising water is rich in nutrients
13. 10.

    What starts coastal upwelling, by Esme's reading (NOAA)?

    • Surface water piling up and sinking
    • Wind pushing surface water away, so deeper water rises
    • Rivers adding fresh water
    • Sea ice melting