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1/ Solar pillar |
The
air in Antarctica is frequently very dry. The low temperatures
mean that little or no water vapour is held in the air,
instead it freezes and falls out, or builds up on surfaces
as frost. Sometimes however depending on the particular
atmospheric conditions, the frozen water vapour remains
in the air as suspended ice crystals. In these conditions
the crystals can reflect sunlight in a variety of ways forming
atmospheric phenomena of different types.
One of these phenomena is the "Solar
Pillar" seen above. The sun is reflected very strongly
so that the reflection is almost as bright as the sun itself.
Like a rainbow, this sight is dependent on where the light
is coming from and where the observer is standing. The pillar
appears to move when the observer moves, but always remains
directly below the sun.
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| 2/ +100°C
water meets -32°C
air |
A
fun thing to do in extreme cold is to throw hot water into
the air. Take a flask and fill it with boiling water
to warm it up, pour this away and fill it again. Take the
full flask outside, take a cup of this hot water and throw
it all up into the air.
As the +100°C
water meets the cold (in this case -32°C) air, it instantly
vaporizes. Most of it is turned into a cloud of steam
that drifts gently away and some of the droplets that stay
together are instantly turned into small pieces of ice that
can be seen streaking down towards the bottom left in this
photograph.
It's very weird to throw water into the air but none of
it ever actually landing. Also seen in this picture is a
solar halo around the sun formed by the ice crystals in
the air.
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| 3/ Heavy seas
across Drakes Passage |
The
Drake Passage is the stretch of water between the most southerly
tip of South America and the most northerly tip of the Antarctic
peninsula. It is
the place where not only are there high and strong winds
that blow most of the time, but where the "Circumpolar
Current" is squeezed through its narrowest gap. This
is a Westerly flowing current that flows around Antarctica
powered by Antarctic winds. It flows at the rate of around
140 million cubic metres (tonnes) of water per second, the
equivalent of 5000 Amazon rivers or four times the size
of the Gulf Stream.
The Drakes passage has been described
as the roughest stretch of water in the world, it is what
must be navigated when rounding Cape Horn and Tierra del
Fuego - the southern most tip of South America. To reach
the Antarctic peninsula it is necessary to traverse this
stretch of water at right angles to the current flow. The
result is often very lumpy seas indeed as seen in this shot
where HMS Endurance is making the crossing.
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4/ Ice mirage |
Mirages
are commonly seen on the horizon in the winter or as in
this case at the end of winter when the sea-ice has just
broken up. They are a result of temperature differences
in the bottom few metres just above the ice or sea surface.
Air of different temperatures
refracts light in different ways, the same phenomena is
responsible for "heat haze" as seen above a road
on a very hot day.
It is the difference in temperature that
is important and in this case it is causing a reflection
downwards just above the level of the horizon so that objects
on the horizon appear to be floating above the sea or ice
rather than resting on it.
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5/ Clouds and skies |
  
I once met someone (admittedly a meteorologist)
who said that his main reason for going to the Antarctic
was because of the amazing skies and clouds that he had
seen in pictures.
Who can blame him? (if not necessarily
agree). The clear (almost) pollution free air and wide open
vistas unencumbered by trees, buildings or other clutter
give panoramas of the sky that stretch for dizzying distances.
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6/ Solar halo |
Another
of the many optical atmospheric phenomena frequently seen
in the Antarctic as a result of the scattering of light
by ice particles suspended in the air.
Such phenomena are usually encountered in
the winter rather than summer when lower temperatures make
such occurrences more likely.
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| 7/ -2°C
water meets -32°C
air |
Another
take on the idea that water turns to vapour when it is considerably
warmer than its surroundings.
In this picture, water is being exposed at
the "tide-cracks" that form around offshore rocks
and small islands when the tide rises and falls with continuous
sea-ice present. As the ice is not flexible it cracks and
as it does, exposes an amount of open water to the air.
Antarctic sea water varies between about
+2°C
and -2°C (approx. the freezing point of sea water)
over the course of a year, so in the case of this picture,
the exposed sea water is more than 30°C warmer than
the surrounding air. The result - it begins to turn to a
vapour being so much warmer. The sunshine on this day serves
to make it more visible and different temperature layers
in the air cause it to rise to a band above the clearer
air close to the ice surface.
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8/ Föhn bank |
A
Föhn bank is formed by a Föhn wind. This is a
warm contour-hugging wind that is blowing across Coronation
Island in the South Orkneys group in this case.
As the warm (relatively to the ice and rock)
wind blows across the land, it causes snow and ice to
sublime. That is to turn directly from a solid to a
gas without passing through a liquid phase, so causing the
cloud layer that can be seen. The overall effect as seen
from a distance is that the land is covered by a very large
duvet. The gross contours can be seen through the cloud
layer, but all of the finer detail is obscured.
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