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The current northern hemisphere cold spell

  1. Jan 12, 2010 #1
    I have heard a couple of different explations from the jet stream moving south to the alantic dipole shifting. Others are saying that the gulf stream has temporarily shifted towards greenland.

    Does anyone have a clear idea of what is going on and more important why there has been this shift in weather patterns this year?
  2. jcsd
  3. Jan 12, 2010 #2


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    Staff: Mentor

    Here is an easy to understand explanation of what caused the cold snap.

    http://www.weather.com/outlook/weather-news/news/articles/why-so-cold-greenland-block_2010-01-11 [Broken]
    Last edited by a moderator: May 4, 2017
  4. Jan 12, 2010 #3
    There Arctic Oscillation is in an extreme negative phase. This makes for a weak polar vortex and allows the Arctic air to descend to lower latitudes. This also means that Arctic temperatures are higher then normal.


  5. Jan 12, 2010 #4


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    The Greenland block is another name/aspect of a negative Arctic Index.
    It produces colder temperatures in Europe and the Eastern Half of North America
    while producing warmer temperatures over the Arctic.

    It is basically a fickle phenomena. No trend in intensity has been found, but it has
    tended to be more positive than negative since the 1970's. So, when it is
    negative, people in North America and Europe tend to notice it.
    Interesting that it recently hit a record since 1950.

    See http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter3.pdf" [Broken] Blocking:

    And also the http://nsidc.org/arcticmet/patterns/arctic_oscillation.html" [Broken]

    Last edited by a moderator: May 4, 2017
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