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; Earth's spin by itself drives them, and winds play no part in it
   • No; wind drives surface currents, and density drives deep ones
   • Correct; salt drives surface currents
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; clockwise in the north, counterclockwise in the south
   • Correct; the Coriolis effect turns the same way everywhere
   • No; gyres turn fastest at the equator
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
   • No; western boundary currents are strong and narrow
   • Correct; western currents are weak
   • Correct; they are broad and slow
4. 4.

   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?

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

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

   • Currents running straight in both hemispheres
   • Gyres turning clockwise in the north and counterclockwise in the south
   • Rivers flowing downhill to the sea
   • Tides rising twice a day
6. 6.

   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
   • A warm western boundary current flowing past
   • Downwelling of warm water
7. 7.

   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?

   • Right on the equator
   • The Southern Hemisphere, turning counterclockwise
   • The Northern Hemisphere, turning clockwise
   • The Southern Hemisphere, turning clockwise
8. 8.

   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
   • Winds drive them; Earth's spin turns them into gyres; western edges run strong
   • Density drives them, and they flow straight
9. 9.

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

   • It is strongest right at the equator
   • Wind turns them the same way everywhere
   • 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
10. 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
    • Wind moves surface water away, and cold, nutrient-rich water rises
    • Cold water sinks and carries nutrients down
    • Wind piles water up against the shore, and warm surface water rises