Surface ocean currents and the Coriolis effect

Grade 9 Science Worksheet - Challenge Me

Circle the best answer.

1. 1.

   A classmate says surface currents are driven mainly by salt differences. Which reply fits NOAA, by Esme's reading?

   • Correct; tides drive each current
   • No; wind drives surface currents, and density drives deep ones
   • Correct; salt drives surface currents
   • No; Earth's spin by itself drives them, and winds play no part in it
2. 2.

   Five gyres on a world map with their turning directions. A student says gyres turn clockwise in both hemispheres. Which reply fits NOAA, by Jun's reading?

   • No; counterclockwise in the north
   • No; gyres turn fastest at the equator
   • Correct; the Coriolis effect turns the same way everywhere
   • No; clockwise in the north, counterclockwise in the south
3. 3.

   A student says western boundary currents are weak and broad. Which reply fits NOAA, by Kira's reading?

   • Correct; they are broad and slow
   • No; western boundary currents are strong and narrow
   • No; they are deep currents driven by salt and temperature
   • Correct; western currents are weak
5. 4.

   A drifter in a western boundary current moves 40 to 120 km a day (about NOAA's 25 to 75 miles). How long does it take to travel 2,400 km, by Luz's math?

   • About 2 to 6 days
   • About 20 to 60 days
   • About 200 to 600 days
   • About 96,000 to 288,000 days
6. 5.

   NOAA: 1 to 3 knots is 1.85 to 5.55 km/h. What is 1 knot in km/h, by Milo's math?

   Use the picture in question 4.

   • 16.65 km/h
   • 1.85 km/h
   • 5.55 km/h
   • 0.54 km/h
7. 6.

   A gyre's loop is about 20,000 km around (model data). At an average 40 km a day, about how long does one loop take, by Noah's math?

   Use the picture in question 4.

   • About 500 days
   • About 5,000 days
   • About 50 days
   • About 800,000 days
8. 7.

   Four evidence cards, labeled A to D. Which evidence best shows the Coriolis effect, by Pia's reading (NOAA)?

   • Rivers flowing downhill to the sea
   • Gyres turning clockwise in the north and counterclockwise in the south
   • Currents running straight in both hemispheres
   • Tides rising twice a day
9. 8.

   Wind pushing surface water offshore as cold water rises. Model map: off a Northern Hemisphere coast, wind blows along the shore, the water is colder than offshore, and fishing is rich. What best explains this, by Ren's reading?

   • Melting sea ice
   • Upwelling of cold, nutrient-rich water
   • Downwelling of warm water
   • A warm western boundary current flowing past
10. 9.

    Which summary of the Coriolis effect fits NOAA, by Ari's reading?

    • Wind turns them the same way everywhere
    • It is strongest right at the equator
    • Earth's rotation turns moving air and water right in the north, left in the south
    • Earth's rotation turns them left in the north and right in the south
11. 10.

    Wind pushing surface water offshore as cold water rises. Which summary of upwelling fits NOAA, by Bo's reading?

    • Rivers push water up from below
    • Cold water sinks and carries nutrients down
    • Wind moves surface water away, and cold, nutrient-rich water rises
    • Wind piles water up against the shore, and warm surface water rises