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Creating an
Earth System I

Creating an Earth System:

Hydrosphere-Atmosphere Interactions

In what way are water and air similar?
They are both fluids.

Review from Session 1

• The Sun is the major source of energy for phenomena on the Earth's surface, powering winds, ocean currents and the water cycle.

• Energy from the Sun heats the Earth unevenly. As a result, convection currents develop in the atmosphere and ocean. These redistribute heat in the atmosphere and oceans.

Where are the storage places or reservoirs for the Earth's water?

• Oceans, rivers, glaciers, aquifers/ground water, atmosphere, and biosphere.

• Oceans are the largest reservoir.

• Frozen hydrosphere is the largest reservoir of fresh water, but ground water is the largest AVAILABLE source of fresh water.

The Water Cycle

The diagram below shows the Earth's water cycle (also knows as the hydrologic cycle). Image courtesey USGS.

What drives surface currents?

Wind circulation

What drives deep-water circulation?

Currents that are density-driven (density depends on salinity and temperature). As the solar energy does not penetrate far into the ocean waters, the water temperature decreases rapidly between 100 and 800 meters, in a region referred to as the thermocline. There may also be a region of rapid change in the salinity, referred to as the halocline.

For more information on these topics, visit: Thermocline and Halocline prepared by Don Reed of San Jose State University.

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