Glacier ice accumulation
Glacier ice accumulation occurs through accumulation of
snowand other frozen precipitation, as well as through other means including rime ice(freezing of water vaporon the glaciersurface), avalanching from hanging glaciers on cliffs and mountainsides above, and re-freezing of glacier meltwateras superimposed ice. Accumulation is one element in the glacier mass balanceformula, with ablation counteracting. With successive years in which accumulation exceeds ablation, then a glacier will experience positive mass balance, and its terminus will advance.
Glaciologists subdivide glaciers into glacier accumulation zones, based on the melting and refreezing occurring. [cite journal | author = Müller, F. | year = 1962 | title = Zonation in the accumulation area of the glaciers of Axel Heiberg Island | journal = Journal of Glaciology | volume = 4 | pages = 302–313 ] [cite book | last = Patterson | first = W.S.B. | title = The Physics of Glaciers | edition = 3rd | year = 1994 | publisher = Pergamon | location = Oxford] These zones include the dry snow zone, in which the ice entirely retains subfreezing temperatures and no melting occurs. Dry snow zones only occur within the interior regions of the Greenlandand Antarctica ice sheets. [cite book | last = Benn | first = Douglas I. | coauthors = David J.A. Evans | title = Glaciers and Glaciation | year = 1998 | publisher = Arnold Publishers| location = London] [cite journal | author = Benson, C.S. | year = 1961 | title = Stratigraphic studies in the snow and firn of the Greenland Ice Sheet | journal = Folia Geographica Danica | volume = 9 | pages = 13–37 ] Below the dry snow zone is the percolationzone, where some meltwater penetrates down into the glacier where it refreezes. In the wet snow zone, all the seasonal snow melts. The meltwater either percolates into the depths of the glacier or flows down-glacier where it might refreeze as superimposed ice. A glacier's equilibrium lineis located at the lower limit of the wet snow zone.
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