|1/ How can this
man stand next to an iceberg?
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
|2/ Why does the
iceberg look different when the sun shines?
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.
|3/ How big is
the "tip of the iceberg"
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%
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
|4/ When is an
iceberg not an iceberg?
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
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.
|5/ How are 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
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.
|6/ Are you sure
this thing's safe?
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!
Antarctica Fact File Index