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Salt of the Earth


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This video from NASA features scientists who describe the role of salt in the oceans and global oceanic circulation, especially the effect of salinity on the density of water and its global circulation, with reference to global climate change.

Video length: 4.75 min.

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Climate Literacy
About Teaching Climate Literacy

Covering 70% of Earth's surface, the ocean exerts a major control on climate by dominating Earth's energy and water cycles. It has the capacity to absorb large amounts of solar energy. Heat and water vapor are redistributed globally through density-driven ocean currents and atmospheric circulation. Changes in ocean circulation caused by tectonic movements or large influxes of fresh water from melting polar ice can lead to significant and even abrupt changes in climate, both locally and on global scales.
About Teaching Principle 2
Other materials addressing 2b
Environmental observations are the foundation for understanding the climate system. From the bottom of the ocean to the surface of the Sun, instruments on weather stations, buoys, satellites, and other platforms collect climate data. To learn about past climates, scientists use natural records, such as tree rings, ice cores, and sedimentary layers. Historical observations, such as native knowledge and personal journals, also document past climate change.
About Teaching Principle 5
Other materials addressing 5b

Energy Literacy

Water plays a major role in the storage and transfer of energy in the Earth system.
Other materials addressing:
2.4 Water stores and transfers energy.

Benchmarks for Science Literacy
Learn more about the Benchmarks

Scientific investigations usually involve the collection of relevant data, the use of logical reasoning, and the application of imagination in devising hypotheses and explanations to make sense of the collected data.
Explore the map of concepts related to this benchmark
Transfer of thermal energy between the atmosphere and the land or oceans produces temperature gradients in the atmosphere and the oceans. Regions at different temperatures rise or sink or mix, resulting in winds and ocean currents. These winds and ocean currents, which are also affected by the earth's rotation and the shape of the land, carry thermal energy from warm to cool areas.
Explore the map of concepts related to this benchmark
In a fluid, regions that have different temperatures have different densities. The action of a gravitational force on regions of different densities causes them to rise or fall, creating currents that contribute to the transfer of energy.
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Notes From Our Reviewers The CLEAN collection is hand-picked and rigorously reviewed for scientific accuracy and classroom effectiveness. Read what our review team had to say about this resource below or learn more about how CLEAN reviews teaching materials
Teaching Tips | Science | Pedagogy | Technical Details

Teaching Tips

  • Good introduction to oceanic 'conveyor belt.'
  • Note that this video pre-dates the launch of the Aquarius mission satellite (on 10 June 2010).
  • Note: this video takes a long time to load in browser, depending on speed of Internet connection. Plan an activity or explanation to share while it loads, or load in advance.
  • Data are available through the NASA Physical Oceanography website: http://podaac.jpl.nasa.gov/SeaSurfaceSalinity/Aquarius

About the Science

  • Video describes the effect of salinity on the density of water and its global circulation.
  • Video presents a strong overview of the oceanic conveyor belt, with state-of-the-science animations showing accurate representations of major oceanic currents.
  • **Note that this video pre-dates the launch of the Aquarius mission satellite (on 10 June 2010). Looking at data from that mission (http://aquarius.nasa.gov/)can be accessed through the impressive NASA Physical Oceanography website: http://podaac.jpl.nasa.gov/SeaSurfaceSalinity/Aquarius

About the Pedagogy

  • Excellent overview. Accurate simplified representations and animations of oceanic circulation are disturbingly rare, and this one gets it right (on a simple level, but it's correct).
  • Lots of data is shown, but not always with appropriate scale or reference keys.
  • Significant vertical exaggeration is included in several of the visualizations without documentation, so this may require some explanation for younger students.

Technical Details/Ease of Use

  • Well-done and effective graphics and animations.
  • Modern, high-quality video.
  • The video can take a long time to load into your browser–allow adequate time for it to load before you need it in class.

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