Transcript GLACIERS AKA ICE SHEETS

GLACIER
 natural accumulation of land ice showing
movement at some time
 great ice sheets have waxed and waned over the
surface of the Earth
 causes for the increase and decrease in ice sheets
are still uncertain, probably not one single thing
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http://www.pbs.org/wgbh/nova/vinson/glac-nf.html
CAUSES OF GLACIATION
 CLIMATE CHANGE
 Earth has experienced many climate changes
 change in Earth temperature and air/water circulation
 decrease of 4o to 5o C (especially summer)
 large increase in the amount of snowfall in subarctic
and arctic regions
SUGGESTED THEORIES FOR CLIMATE CHANGE
 reductions in solar radiation due to meteorite
collisions with the Earth,
 increased volcanism
 shifting location of continents
 uplift of vast mountain regions
 Milankovitch Cycles
MILANKOVITCH CYCLES
 Milutin Milankovich – Serbian Astrophysicist
 thought to cause the necessary change to decrease global
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temperatures.
Earth's orbit is elliptical, over periods of 100,000 years the
shape varies
changes in orbit have been matched with ocean sediments
that record the history of glacial stages
cycles of warming and cooling match with the estimated
dates of glacial periods
Earth "wobbles" on its axis which alters the amount of solar
radiation reaching the Earth
Ice Sheet Structure
 zone of accumulation, the portion of the glacier over
which accumulation exceeds ablation
 zone of ablation is the loss of ice (or snow) from the
glacier
 equilibrium line is the boundary between these two
zones
 If accumulation > ablation the glacier will grow
 If ablation > accumulation, the glacier will retreat
Ice Sheet Structure
Continental
 Form on continents, flat land
Global distribution of continental glaciers
Ellesmere Island, Canada
Alpine
 Form in mountains
Jungfrau, Switzerland
Nisqually , Mount Ranier
Piedmont
 Form by combining of alpine glaciers
Malaspina Glacier, Alaska (landsat)
Switzerland
Icebergs
 Pieces of glaciers that have broken
off into water.
 Do you know what this process is
called?
Glacier Bay , Alaska
Ablation
 sublimation - solid to gas, ice (firn) to water vapor
 wind erosion – just like sand blowing away on a beach
 melting – ice changing from solid to liquid form
 evaporation - liquid to gas
 calving – process of glaciers breaking off into bodies of
water, produces icebergs
Sublimation
Ablation on Glacier de Tsanfleuron, Switzerland
Calving
What makes glaciers melt?
 List at least 3 things in your notes
REFERENCES
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http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/glacial_systems/glaciation_causes.html
http://www.worldviewofglobalwarming.org/pages/glaciers.html
http://www.commondreams.org/headlines02/0925-05.htm
http://www.space.com/scienceastronomy/planetearth/pumpkin_planet_021205.html
http://www.uwsp.edu/geo/faculty/ritter/geog101/uwsp_lectures/lecture_glacial_processes.html
http://www.swisseduc.ch/glaciers/glossary/ablation-en.html
http://www.pbs.org/wgbh/nova/vinson/glac-nf.html
http://www.swisseduc.ch/glaciers/glossary/ablation-en.html