Sometimes I complain about the earthly weather, but mostly I like to post about astronomy and space events. Hope you enjoy the articles.
By: Susie77 , 8:02 PM GMT on February 16, 2012
Europe Hammered by Winter, Is North America Next?
Feb 16, 2012: For the first half of this year's winter, the big news was warm temperatures and lack of snow. Ski resorts were covered in bare dirt, while January temperatures in southern California topped July highs.
Then, out of the blue, Europe got clobbered: Over the past two
weeks, temperatures in Eastern Europe have nose-dived to -30 degrees
Celsius (-22 degrees Fahrenheit). Blizzards and the bone-chilling cold
have resulted in the deaths of over 550 people so far, with rooftop-high
snow drifts trapping tens of thousands of villagers in their homes and
cutting off access to entire towns. It has even snowed as far south as
This map shows temperature anomalies for Europe and western
Russia from January 25 to February 1, 2012, compared to temperatures for
the same dates from 2001 to 2011. The anomalies are based on land
surface temperatures observed by the MODIS instrument on NASA’s Terra
NASA climatologist Bill Patzert of the Jet Propulsion Laboratory
explains what happened: "A couple of weeks ago, Mother Nature did an
about face. The tight polar vortex that had bottled up the cold arctic
air in the beginning of winter suddenly weakened. Cold air swept out of
Siberia and invaded Europe and the Far East."
The "tight polar vortex" is caused by the Arctic Oscillation (AO),
a see-sawing pressure difference between the Arctic and lower
latitudes. When the pressure difference is high, a whirlpool of air
forms around the North Pole. That’s what happened earlier this winter:
the whirlpool was more forceful, corralling the cold air and keeping it
nearer the pole.
An artist's concept of the Arctic Oscillation in its negative phase. [more] [video]
Now the vortex is weakening. With "the AO Index going negative,"
as an expert or weather-nerd might put it, cold air escapes from that
whirlpool and heads southward, resulting in the killing extremes now
plaguing the other half of the planet.
However, even the breakdown of the vortex cannot completely
account for the severity of the winter Europe is suddenly experiencing.
As strange as it sounds, some climatologists, among them Judah Cohen of
Atmospheric and Environmental Research in Massachusetts, attribute the
unusual cold to global warming. Cohen contends that since sea ice is
being melted by warmer temperatures in the Arctic, more moisture is
available for the atmosphere to pick up – and drop as snow. As a result,
Siberian snow cover has increased, and this snow cover has a cooling
effect which reaches East Asia and Europe.
"Cohen's research is cutting edge and could bring important
improvements to forecasting climate and weather over North America and
Europe," says Patzert. "Cohen and others are on the threshold of
understanding of how climate change affects the behavior of the Arctic
Patzert adds, however, that this winter is just one of many severe
winters that have changed European history. "Looking back, Mother
Nature has taken us on some very wild rides."
He cites the winter of 1683/84, when the Thames River in England
stayed frozen with a thick layer of ice for nearly two months, as an
If only Napolean had a weather satellite.... [more]
"And let’s not forget the frigid winter of 1812, when Napoleon's
Grande Armee was decimated by the extreme cold in Western Russia."
Patzert notes that European history would have been much different
if Napoleon had had a good meteorologist on his staff and some NASA
satellites to warn him about what he was marching into.
"And the turning point of World War II occurred in 1941, when Germany’s forces were nearly frozen in place," he adds.
There are many other examples2, and climate change can't be blamed for all of them.
"There's always going to be some natural variability. Every
episode of high temperatures or extreme cold isn't climate change.
Sometimes it's just weather!"
The weakening Arctic Oscillation could soon bring a return of
winter to North America as well, although Patzert doesn't expect it to
be as severe as what's happening on the other side of the Atlantic.
Is there any relief in sight for Europe?
"The good news is that this crippling cold snap arrived
mid-winter. With the vernal equinox less than six weeks away, this AO
episode will become muted – hopefully."
Hang on till Spring."
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