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1/ How can this
man stand next to an iceberg? |
 Ice-bergs
drift around the Southern Ocean carried by the currents and blown by the
winds.
In the winter the sea-ice freezes around them and effectively
glues them in place until the spring when the ice breaks up and they can
begin to move again.
During this frozen-in time, it is possible to travel out
across the sea-ice and walk right up to the bergs.
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2/
Why does the iceberg look different when the sun shines? |
 It
can be quite magical standing next to an ice-berg, especially when the sun
is shining and glistening off the ice.
The sun can also penetrate the ice and be reflected off
inner surfaces giving a whole variety of effects and colours from white
through a range of vivid blues, quite an unreal experience.
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3/ How big is
the "tip of the iceberg" |
 The
tip of the "ice-berg." Everybody knows that most of an iceberg lies under
the water, but most don't know that the amount beneath the surface varies
from about 50% to 99%.
The cause of the variation is largely in the amount of
air that is trapped in the ice so affecting its buoyancy. An average iceberg
will be about 80-90% beneath the surface. Very low lying pieces of ice of
whatever size in the water are known as "growlers". These often have a green
tinge to them. They are known as growlers because they present a particular
hazard to shipping with the small amount visible above the water and the
dark colour making them especially difficult to see and therefore especially
dangerous.
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| 4/
When is an iceberg not an iceberg? |
 There
are lots of different names for different kinds of ice. Large pieces
of ice that were once part of an iceberg that broke up are known as "bergy
bits" if they are too small to be considered as icebergs themselves
(I never did discover when a "bergy bit" was big enough to be a "berg",
I think it's a matter of opinion!). These
bergy bits in the picture are trapped in the frozen sea-ice in the winter
making it possible to walk out to them. In the distance can be seen trapped
icebergs and the long low landmass of a nearby island, the two peaks to
the left are about 40 miles (64 kilometers) way.
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| 5/ How are icebergs
made? |
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 Icebergs
are made of freshwater ice and not of frozen sea water. They form from
the edge of glaciers when the glacier reaches the sea and either breaks
off in pieces to form an iceberg, or in the case of an ice shelf, begin
to float on the sea and then breaks off from the rest of the glacier as
a large slab.
Icebergs are made up of snow that has fallen over many
hundreds or even thousands of years. The stripes and different coloured
layers in icebergs represent different layers of snowfall and the weather
conditions under which the snow fell. If it is very cold then a light open
layer with much air included will be formed, this gives a paler or white
layer. The darker, bluer layers come from snow fall in relatively warm,
maybe even wet conditions when little or no air is trapped in the layer.
In addition to this, air is squeezed out of the lower
layers of a glacier as more and more snow falls and so the weight of snow
builds up.
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6/ Are you sure this thing's
safe? |
 Standing
next to an iceberg such as this one can be quite a scary experience.
In addition to being stuck in the sea ice, this particular berg has been
grounded on the sea bed. It was probably blown towards shore by strong winds
or a storm, and on a high tide. When the wind died down and the tide fell,
the berg was left resting, stuck on the sea bed.
A result of this is that when the tide rises and falls the
sea ice rises and falls with it but the iceberg doesn't. There are all kinds
of creaking and groaning noises made by the sea ice as it is forced to rub
up and down the uneven sides of the berg with the tide. To add to these
unsettling sounds are an assortment of creaks, groans and bangs made by
the iceberg above water as the sun heats up the surface.
The fear is that either a large lump of ice will come
tumbling down or worse still, the iceberg becomes unstable and tips up to
a new more stable position. This tipping up rarely happens in the winter,
more commonly it takes place in warmer summer temperatures, but it is not
unknown and if it happens can cause waves and ripples that break up the
surface of the sea ice for miles around. Neither of these events are ones
that you want to witness while standing on the sea ice surrounding the iceberg!
Icebergs 2
Antarctica Fact File Index
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