Transcript Types of ice

TYPES OF ICE
• The ‘cryosphere’ refers to the places in the
world where H2O is usually in the frozen state.
• This includes areas of snow, glaciers, sea ice,
and permafrost.
• These slides show photographs and images so
that you can learn about different types of ice,
and where these types are found.
You can learn more about the cryosphere at this website:
http://www.discoveringthearctic.org.uk/9_what.html
Polar regions
• Most of the world’s ice is in the form of glacier
ice and is found in the polar regions.
• 85% of the total area of the world covered in
glacier ice is the Antarctic ice sheet. Greenland
accounts for 11% of the area covered by
glaciers.
• Glaciers in other parts of the Arctic and in high
mountains of the world (e.g. Himalayas,
Andes, Rockies, Alps) account for 4% of total
glacier area.
Key point: ‘glacier ice’ is not the same as snow,
And not the same as frozen ocean (sea ice).
Images of Antarctica and Greenland (not to scale)
http://www.discoveringantarctica.org.uk/alevel_1_1.html
(http://www.climatechange.umaine.edu/Research/projects/Greenland/gr
onland3d.jpg)
Images not compared to scale
Antarctica (85% of all glacier ice
cover on Earth, 13.5 mill km2) About 75% of the world’s freshwater is locked up in glacier ice!
If all of the Antarctic ice sheet melted, sea level would rise by over 60 metres. You can
check the effect of this on coastlines at this website:
http://flood.firetree.net/
On the Antarctic ice sheet, looking at the Transantarctic
mountain range
http://commons.wikimedia.org/wiki/File:NOAA_Royal_Society_Range.
jpg?uselang=en-gb Michael Van Woert
Map showing the Transantarctic mountain range and
location of Antarctica’s largest ice shelves
http://upload.wikimedia.org/wikipedia/commons/f/fc/Map_of_Transa
ntarctic_Mountains.jpg?uselang=en-gb
At the edges of the Antarctic ice sheet (and parts of the Greenland ice sheet)
glaciers reach the sea and float out over the water to form ice shelves. This is
not the same as frozen sea water.
ice shelf
http://commons.wikimedia.org/wiki/File:Getz_Ice_Shelf.jpg?uselang=en-gb NASA/Dick Ewers
At the edges of the ice shelves chunks of glacier ice break off and float out to
sea: these chunks of ice are called icebergs. They form by a process called
‘iceberg calving’.
http://commons.wikimedia.org/wiki/File:Iceberg_Antarctica.jpg?uselang=en-gb Ben Stephenson
Sea ice is completely different from an ice shelf. Sea ice forms as the top layer
of the ocean freezes in winter. The area of sea ice in the Arctic Ocean and the
Southern Ocean changes hugely with the seasons. Some sea ice in the coldest
areas stays frozen all year.
Broken up sea ice, Ross Sea, Antarctica
http://commons.wikimedia.org/wiki/File:Sea_ice_in_ross_sea.jpg?uselang=en-gb Brocken Inaglory
This image shows more continuous sea ice.
http://upload.wikimedia.org/wikipedia/commons/1/13/CryoSat_sea_ice_Weddell_Sea_D7000_D
SC0781_%286245410446%29.jpg?uselang=en-gb
These images give a rough idea of the extent of winter sea ice in
each hemisphere.
http://commons.wikimedia.org/wiki/Category:Sea_ice#mediaviewer/File:North_pol
e_february_ice-pack_1978-2002.png
http://commons.wikimedia.org/wiki/Category:Sea_ice#mediaviewer/File:S_200806_con
Winter sea ice, N.H.
To watch an animation of changing
sea ice in the Northern Hemisphere follow this:
c.png
Winter sea ice, S.H.
http://commons.wikimedia.org/wiki/File:Arctic_sea_ice_los
s_animation.gif?uselang=en-gb
In large parts of the Northern Hemisphere, there is frozen water in the
ground. Areas are called ‘permafrost’ if ground remains below 0°C for
at least two consecutive years.
• purple region : permafrost
• blue regions : seasonally frozen ground (the
soil is frozen for 15 days or more per year)
• pink regions : intermittently frozen ground (
the soil is frozen for fewer than 15 days per
year)
• solid line : the average maximum extent of
the seasonal snow cover
NASA modified image
http://commons.wikimedia.org/wiki/File:Froze
nground.gif?uselang=en-gb
Area of permafrost with ‘ice wedge polygons’ and thaw ponds on the
ground’s surface (northern Canada). (Photo from an aeroplane.)
http://commons.wikimedia.org/wiki/File:Ice_Wedges_(Polygonal_Terr
ain)_in_Mackenzie_Delta__Viewed_from_Cessna_172_en_route_from_Inuvik_to_Tuktoyaktuk__Northwest_Territories_-_Canada.jpg?uselang=en-gb Adam Jones
Mountain regions
• Snow, glaciers, frozen lakes, and permafrost are
also found at high altitudes outside of the polar
regions.
• This is because air temperature goes down as you
gain altitude (go up) through the lower
atmosphere.
• Because it is warmer near the equator, the closer
you are to the equator, the higher a mountain has
to be before the air is cold enough for snow
patches and glaciers to form on it.
Global location of glaciers:
latitude and altitude
This graph gives a simple summary of how
the altitude (height above sea level) where
glaciers can form increases as you get closer
to the equator.
Height above sea level
5 km
0°
Equator
Latitude
90°
North Pole
Mt Kilimanjaro (Tanzania) is near the equator, reaches
http://commons.wikimedia.org/wiki/File:Kibo_summit_of_Mt_Kiliman
5892 m above sea level
jaro_001.JPG
(snow can survive the summer from approx. 5500 m altitude)
This NASA satellite image shows large areas of Asian mountains covered by glaciers
http://commons.wikimedia.org/wiki/File:High_Asia_Mountain_Ranges.jpg?uselang=en-gb NASA/Rupert Pupkin
Mt McKinley, Alaska
The altitude of snow and glaciers is a lot lower than in the previous image of
Mt Kilimanjaro because Alaska is much further from the equator.
http://commons.wikimedia.org/wiki/File:MountMcKinley_BA.jpg?uselang=en-gb
Some high mountain ranges of the world
with glaciers
Rockies
Alps
Andes
Himalayas
Southern Alps (NZ)
http://commons.wikimedia.org/wiki/World_map#mediaviewer/File:Eckert4.jpg