Compare two parcels at the same pressure. In the simplified comparison, a cooler or saltier parcel is denser than an otherwise similar warmer or fresher parcel. Surface currents respond strongly to wind, while deep circulation involves density differences, mixing and the shape of the ocean basins.
Water and oceans · Discover & try
What can move water across the ocean?
Reading level 2 of 5 · DevelopingChange
Word help
Density
Mass per unit volume.
Surface current
Water movement near the ocean surface, often strongly affected by wind.
Overturning
Circulation connecting shallower and deeper water.
Watch · Try · Explain
See how it works
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Conceptual wind and relative-density views; not a map or numerical seawater-density calculation.
What to look for
- Compare the parcel with surrounding water.
- Change temperature without changing salinity.
- Distinguish wind-driven surface movement from sinking.
Explain what you noticed
Two nearby parcels have the same salinity and pressure. One cools while the other does not. What tendency fits ordinary seawater conditions?
Keep this idea: Wind drives much surface circulation; temperature and salinity help influence water density and deeper movement.
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Source material checked 2026-10-28. Explanations and activities by Nepedia. Source links do not imply endorsement.
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