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  • If youve been hearing that extreme cold spells like the one that were having in the United States now,

  • disprove global warming, don’t believe it.

  • The fact is that no single weather episode can either prove or disprove global climate change.

  • Climate is the pattern of weather that we observe geographically

  • and over the seasons, and it’s described in terms of averages, variations, and probabilities.

  • But a growing body of evidence suggests that the kind of extreme cold being experienced,

  • By much of the United States as we speak is a pattern that we can expect to see,

  • With increasing frequency as global warming continues.

  • And the reason is this: in the warming world that were experiencing,

  • the far north, the Arctic, is warming roughly twice as rapidly as the mid-latitudes such as the United States,

  • That means that the temperature difference between the Arctic and the mid-latitudes is shrinking.

  • And that temperature difference is what drives what is called the circumpolar vortex,

  • which is the great counterclockwise-swirling mass of cold air that hovers over the Arctic.

  • As the temperature difference between the Arctic and the mid-latitudes declines,

  • the polar vortex weakens, and it becomes wavier.

  • The waviness means that there can be increased larger excursions of cold air southward

  • that is into the mid-latitudes and in the other phase of the wave,

  • Increased excursions or relatively warmer mid latitude air into the far north.

  • Computer models tell us that there are many different factors influencing these patterns.

  • And, as in all science, there will be continuing debate about exactly what is happening.

  • But I believe the odds are that we can expect as a result of global warming,

  • to see more of this pattern of extreme cold in the mid-latitudes

  • and some extreme warm in the far north.

If youve been hearing that extreme cold spells like the one that were having in the United States now,

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B1 US WhiteHouse mid warming arctic vortex global warming

The Polar Vortex Explained in 2 Minutes

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    Go Tutor posted on 2014/01/20
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