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?

   • No; wind drives surface currents, and density drives deep ones
   • Correct; tides drive each current
   • 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; gyres turn fastest at the equator
   • No; clockwise in the north, counterclockwise in the south
   • No; counterclockwise in the north
   • Correct; the Coriolis effect turns the same way everywhere
3. 3.

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

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

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

   • 16.65 km/h
   • 5.55 km/h
   • 0.54 km/h
   • 1.85 km/h
6. 5.

   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 50 days
   • About 500 days
   • About 800,000 days
   • About 5,000 days
7. 6.

   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
   • Tides rising twice a day
   • Currents running straight in both hemispheres
8. 7.

   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
   • A warm western boundary current flowing past
   • Downwelling of warm water
   • Upwelling of cold, nutrient-rich water
9. 8.

   Model map: a warm, fast, narrow current flows north along an ocean's west side, and a cool, slow, broad one flows south along its east side. Which hemisphere is this gyre in, by Tala's reading?

   • The Southern Hemisphere, turning clockwise
   • The Southern Hemisphere, turning counterclockwise
   • Right on the equator
   • The Northern Hemisphere, turning clockwise
10. 9.

    World map with current arrows. Which summary of surface currents fits NOAA, by Zee's reading?

    • Winds drive them; the eastern edges run strong and narrow
    • Winds drive them; gyres turn the same way in both hemispheres
    • Density drives them, and they flow straight
    • Winds drive them; Earth's spin turns them into gyres; western edges run strong
11. 10.

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

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