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North and South Pole Differences
Name: John
Status: Educator
Age: 30s
Location: Oregon
Country: United States
Date: January 9, 2005
Question:
Hello - Today, while teaching my 5th grade students about
the cause of seasons, I was unable to answer a question. The question was:
"If the North and South Pole are receive equal amounts of sunlight at
equal angles over the course of the year, why when looking at a globe do
we observe far more ice/snow at the South Pole than at the North
Pole? Obviously there is a land mass at Antarctica which is part of the
reason, but we see many "green" land areas in the North that are at a
distance from the Pole that, were they at that distance from the South
pole they would be covered with snow/ice.
What is going on here?
Is it
colder at the South Pole?"
Replies:
Jon -
You may find someone with more expertise than I to answer this questions,
but I would attribute your student's excellent observation to what you
noted. Under the North pole there is an ocean that never freezes solid.
This allows the north pole to be warmed from the lower latitudes of the
earth not only by air currents, but also by ocean currents. The amount of
heat (remember heat is different from temperature) stored in water is much
greater than what can be stored in like amounts of air. This element is
missing at the south pole where there is a continent below.
You may notice that large buildings are generally heated with hot water
systems. This is because it is a more efficient means of moving heat. In a
house, the difference is not pivotal, but in larger buildings the savings
makes it economically worthwhile to use a more expensive hot water system.
Your observation of the two poles receiving essentially the same solar input
(called insolation... not insulation!) is correct.
Three cheers for a good observation and excellent question from your
student.
Larry Krengel
Jon,
There are many reasons for the difference in ice cover
between the Arctic and Antarctica.
The land area of Antarctica happens to be at the pole
and is surrounded by water, whereas there is little
land area in the Arctic (it is mostly water covered).
The land cover of Antarctica can more easily accumulate snow
(and therefore ice) since, once the soil is frozen, snow can
readily accumulate. The Arctic, being sea water (salty)
requires a lower temperature than the freezing temperature
of pure water, and therefore more time, to freeze than
would the land surface of Antarctica.
The geography and meteorology of the northern and southern
hemispheres are also quite different, because there is more
land mass in the northern hemisphere. The more land, the
more heat energy is stored and therefore the longer it
takes to cool the hemisphere in the winter. Because of the
salt water in the Arctic and the greater amount of land
mass in the northern hemisphere, the Arctic would therefore
not cool as rapidly (or as much) as Antarctica and therefore
could not develop as much ice.
Furthermore, being a land mass, Antarctica can accumulate
glaciers, whereas the Arctic can not.
The meteorology of the southern hemisphere is less dynamic
than the northern hemisphere because of there being less land
mass in temperate areas (where most of the dynamic weather
occurs in the northern hemisphere). Therefore, Antarctica
gets locked into very long term circulations around the pole,
which doesn't allow warmer air to penetrate in the wintertime,
helping to keep it cooler there than in the Arctic, and
thereby allowing more ice to accumulate.
Because of all of the above, over all, it is colder in
Antarctica than it is in the Arctic.
David R. Cook
Atmospheric Physics and Chemistry Section
Environmental Research Division
Argonne National Laboratory
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