Deep ocean currents: cold, salty water sinks

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. 1.

   The global conveyor drawn on a world map. What does the word thermohaline refer to, by Ari's reading (NOAA)?

   • Temperature and salinity
   • Tides and the pull of the Moon
   • Wind and waves
   • Depth and pressure

2. Read this first

   Use this

   Wind arrows above, density arrows far below.

3. 2.

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

   • Rivers
   • Tides
   • Differences in density from temperature and salinity
   • Strong surface winds blowing steadily across the open ocean
4. 3.

   NOAA: winds drive currents in the upper 100 m. Where do the density-driven currents flow, by Kira's reading?

   • Inside rivers
   • Thousands of meters below the surface
   • Near the surface, pushed along by the wind
   • Just in the top 100 m
5. 4.

   Which water is densest and sinks, by Jun's reading (NOAA)?

   • Warm, salty water
   • Cold, fresh rainwater
   • Warm, fresh water
   • Cold, salty water
6. 5.

   Sea ice forming above saltier, sinking water. When sea ice forms, what happens to the salt, by Luz's reading (NOAA)?

   • It turns into fresh water
   • It freezes into the ice
   • It rises into the air
   • It is left behind, making nearby water saltier

7. Use this

   The global conveyor drawn on a world map.

8. 6.

   Where does the global conveyor belt start, by Noah's reading (NOAA)?

   • In the middle of the Indian Ocean
   • Near the pole in the North Atlantic
   • At the mouth of a river
   • At the equator in the Pacific
9. 7.

   Where is the conveyor recharged with more cold, dense water, by Pia's reading (NOAA)?

   • Off a tropical island
   • In the warm Indian Ocean
   • Around Antarctica
   • At the equator
11. 8.

    About how long does a cubic meter of water take to complete the conveyor, by Ren's reading (NOAA)?

    • About 10 days
    • About 1 year
    • About 1 million years
    • About 1,000 years
12. 9.

    NOAA: the conveyor moves a few cm a second; wind and tidal currents move tens to hundreds. Which is slower, by Tala's reading?

    Use the picture in question 8.

    • Wind-driven currents
    • The conveyor
    • Tidal currents
    • They move at the same speed
13. 10.

    The global conveyor drawn on a world map. NOAA: the conveyor moves more than 100 times the flow of the Amazon River. If the river's flow is 1 unit, how much does the conveyor move, by Esme's math?

    • About 10 units
    • More than 100 units
    • About 1 unit
    • Less than 1 unit