The oceans and atmosphere

The oceans and atmosphere are incredibly important for sustaining life on Earth. Reservoirs for chemical and energy exchanges, the oceans and atmosphere are both critical in determining the climate now and into the future.

Five distinct layers of the atmosphere have been identified, bounded by "pauses" where the greatest changes in thermal characteristics, chemical composition, movement, and density occur. Most of the atmosphere is contained within a relatively shallow envelope of gases, microscopic solid particles, and liquid particles called aerosols, that surround the globe, known as the troposphere. The atmosphere is comprised largely of nitrogen and oxygen, with water vapour, argon, carbon dioxide and many other gases also present.

The relatively intense warming by the sun of regions near the equator compared to the higher latitudes provides the energy for massive air movements. As air is warmed by the land and oceans near the equator it rises, reaching the top of the troposphere and spreading northward and southward. Eventually it cools and sinks back to the ground again. A well-defined global circulation pattern consists of a series of cells, the largest extending from the equator to between 30 and 40 degrees north and south, are named Hadley cells. Additional cells assist in transferring vast quantities of heat from the tropics to the poles.

The Earth’s climate also depends on energy exchanges between the ocean, the atmosphere, the land and the biosphere. The oceans play a vital role in transferring heat around the globe. For example, the thermohaline circulation involves deep-ocean currents driven by differences in the water’s density, which is controlled by temperature and salinity. Regional currents affect local climate. The East Australian Current moves warm water from the tropical Coral Sea down the east coast of Australia. The Leeuwin Current flows southwards off the western coast of Australia. Another important ocean-atmosphere coupling phenomenon is the El Niño-Southern Oscillation.

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Page last updated 13^th January 2022