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)?

   • Depth and pressure
   • Temperature and salinity
   • Wind and waves
   • Tides and the pull of the Moon
2. 2.

   Wind arrows above, density arrows far below. What drives deep-ocean currents, by Bo's reading (NOAA)?

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

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

   • Warm, fresh water
   • Warm, salty water
   • Cold, fresh rainwater
   • Cold, salty water

4. Read this first

   Use this

   Sea ice forming above saltier, sinking water.

5. 4.

   When sea ice forms, what happens to the salt, by Luz's reading (NOAA)?

   • It is left behind, making nearby water saltier
   • It turns into fresh water
   • It freezes into the ice
   • It rises into the air
6. 5.

   Why does water near forming sea ice sink, by Milo's reading (NOAA)?

   • It gets colder and saltier, so its density rises
   • The wind pushes it down
   • It gets fresher and lighter
   • It warms up and expands
7. 6.

   The global conveyor drawn on a world map. Where is the conveyor recharged with more cold, dense water, by Pia's reading (NOAA)?

   • Around Antarctica
   • At the equator
   • In the warm Indian Ocean
   • Off a tropical island
9. 7.

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

   • About 10 days
   • About 1,000 years
   • About 1 year
   • About 1 million years
10. 8.

    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 7.

    • The conveyor
    • They move at the same speed
    • Tidal currents
    • Wind-driven currents
11. 9.

    A deep current moves 2 cm a second (example data). How far does it go in 1 hour, by Zee's math?

    • 2 m
    • 72 m
    • 120 cm
    • 7.2 km
12. 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
    • Less than 1 unit
    • About 1 unit