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What's Current

What's Current?

Reviewing the Big Ideas

The Earth is a dynamic structure.

The Earth is composed of four spheres: lithosphere/geosphere, hydrosphere, atmosphere, and biosphere, which interact as part of a complex and dynamic system.

Change is evident in all the spheres of the Earth.

Changes are the result of internal and external energy sources.

Convection currents drive movements within the lithosphere, hydrosphere, and atmosphere.

  • The central core of the Earth is the internal source of energy that drives convection currents within the lithosphere, which in turn drive plate movement.

  • The sun is the external source of energy that causes convection currents, which drive the winds, ocean currents, and the water cycle.

The Earth receives more solar energy at the Equator than at the poles.

  • The difference in solar energy levels causes a temperature difference between the Equator and the poles.

  • This temperature difference causes oceanic and atmospheric circulation.

  • Winds and oceans transport heat from low latitude regions to high latitude regions.

Ocean currents are caused by winds, differences in temperature, and differences in salinity.

  • Cold water is denser than warm water.

  • Salty water is denser than fresh water.

  • Cold water near the poles is denser and tends to sink.

  • Surface water from lower latitudes flows poleward to replace sinking cold water.

Because of the rotation of the Earth, ocean currents and winds are deflected to the left or the right of motion.

Climates are strongly influenced by ocean currents.


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