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The global distribution of cold environments
- Glaciers are moving
bodies of ice formed
by accumulation of
snow on ground's
surface
- Past distribution of glaciers
- Areas of glacial activity expand and contract due to climate change
- The earth has experienced
a number of major periods of
ice activity, 'glacials', roughly
every 200-250 million years
- The last ice age ended 10,000 years ago. Ice age at
maximum extent 18,000 years ago covering UK in
north and as far south as British Channel
- Areas of glacial activity expand and contract due to climate change
- Possible reasons for climatic fluctuations leading to ice ages
- Changes in Earth's orbit and tilt
- Variations in sunspot activity
- Variations in ocean currents
- Trapping of CO2 by oceans - reducing amount
in atmosphere and cooling planet
- Changes in Earth's orbit and tilt
- Present day distribution of glaciers
- The distribution of glaciers
today is climate controlled;
existing where temperatures
are cold enough to allow yearly
accumulation of ice to exceed
the process of ablation (growth
occurs where
accumulation>ablation)
- Areas of high altitude -
atmospheric pressure falls with
increased altitude, expansion in
volume of air and decreasing
temperatures. Alps, Andes and
Himalayas have glaciers.
Glaciers can even exist at
equator above 5000m due to
conditions at high altitude; e.g.
Cotopaxi Volcano - Ecuador
- Areas of high latitude where
annual temperatures low and high
albedo, reflecting large amounts
of solar radiation back to space
- Antarctica and Greenland
- Antarctica and Greenland
- The distribution of glaciers
today is climate controlled;
existing where temperatures
are cold enough to allow yearly
accumulation of ice to exceed
the process of ablation (growth
occurs where
accumulation>ablation)
- Types of glacier - classified according to size and area they occupy
- Ice sheets - largest feature - continental sized accumulation above 50,000km2 e.g. Antarctica ice sheet
- Ice caps - huge domed
shaped masses of ice on
high plateaus
- Ice field - much of an
upland area covered by
glacial ice with just tallest
peaks exposed (nunataks)
- Valley glacier -
large masses of ice
flowing from ice
fields or cirque;
often following
pre-glacial river
valley
- Corrie glacier - small
ice masses on N-NE
facing mountain
slopes, covering
area usually 0.5 to
10km2, gradually
eroding hollows
through glacial
erosion
- Piedmont glacier - large lobes of
ice formed when glaciers spread
out on reaching lowland areas and
escape confines of valley
- Ice shelves -
extensions of ice
sheets reaching out to
sea up to 1000m thick
- Ice sheets - largest feature - continental sized accumulation above 50,000km2 e.g. Antarctica ice sheet
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