Australia: The Land Where Time Began

A biography of the Australian continent 

The Cryosphere - Effects on the Hydrological Cycle

Moisture that is precipitated as snow is an integral part of the hydrological cycle, including the precipitation of the lower latitudes, much of which originates as atmospheric snow crystals. Temporary water storage in snow cover on the continents and on sea ice, that delays the return of the water to the oceans by weeks or months, is one of the main effects of snow cover on the global hydrological cycle. On the continents water can be locked up in glaciers for years to millennia The hydrological catchments that are dominated by snow melt rivers reach their peak flows in the spring freshet, at which time the snow-melt reaches its maximum. In late summer this is supplemented by glacier meltwater, and in the tropics, in the dry season(s).

There are a number of ways in which regional climates are affected by lakes and oceans. In winter a source of longwave and sensible heat fluxes that moderate the local climate in coastal areas, and locations adjacent to major lakes, is provided by open water. Once sea ice or lake ice forms this effect is lost. A source of water is also provided by open water, increasing the downwind snowfall. This effect has been found to occur in the Great Lakes of North America, in Baffin Bay in coastal ice caps adjacent of the North Water Polynya, and in southeastern Greenland. According to the author1 atmospheric moisture and snowfall are expected to increase at high latitudes as the global temperature rises and sea ice is lost, resulting in a climate-change feedback that makes the system unpredictable. A positive influence on glacier mass balance results from increased snowfall, and a negative influence on the thickness of permafrost, and mixed effects on the thickness of lake ice and sea ice, all depending on the seasonality of the snow cover. In winter the ice is insulated by a deeper snowpack, which limits its growth.

As a result of snowpack loading and submergence snow ice formation has opposite effects on the thickness of the ice. Thicker ice is also promoted by snowfall on lake ice, sea ice, and glaciers in spring and summer as it helps limit the melting as a result of increased albedo.


Sources & Further reading

  1. Marshall, Shawn J., 2012, The Cryosphere, Princeton University Press. 


Author: M. H. Monroe
Last updated 30/04/2013

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