DISCUSSION: There is no question that within the last 7 to 10 days, millions and millions of people across a substantial portion of North America experienced the full force of the atmospheric larger-scale circulation which is known as the Polar Vortex. Despite the large variety of ways in which various media platforms have continued to discuss and try to explain the presence as well as the impacts of the Polar Vortex, it is imperative to fully break down what the Polar Vortex is and how scientists physically study its structure and its corresponding impacts.
To start, the Polar Vortex is most fundamentally a larger-scale stratospheric circulation (i.e., an atmospheric circulation located within the layer of the atmosphere which is positioned directly above the troposphere which is where the majority of the Earth’s weather occurs) which somewhat oscillates in its position in the Arctic and Antarctic regions during the course of the Winter-time months in the respective hemispheres. During a given Winter-time season, there are stronger Arctic low-pressure systems which periodically develop over the Arctic and Antarctic regions of the world. As these powerful low-pressure systems develop and sometimes persist, such systems can often help to trap very cold air in and around the Arctic and/or Antarctic regions. However, when these powerful upper-level circulations occasionally become weaker and increasingly more unstable under the right circumstances, this can quickly lead to situations defined by the release of severe cold air intrusions into many parts of North America, Europe and beyond.
Attached above is a neat graphic and an exact excerpt which was produced and written by the National Oceanic and Atmospheric Administration (NOAA) which perfectly encapsulates the general physics and dynamics of the Polar Vortex in both the Northern and Southern Hemisphere. “The polar vortex is a large area of low pressure and cold air surrounding the Earth's North and South poles. The term vortex refers to the counter-clockwise flow of air that helps keep the colder air close to the poles (left globe). Often during winter in the Northern Hemisphere, the polar vortex will become less stable and expand, sending cold Arctic air southward over the United States with the jet stream (right globe).” You will also notice how the episodic descent of colder air masses into the mid-latitudes (i.e., where most of the world’s population lives) is often contingent on regional and larger-scale fluctuations with respect to both temperature and pressure regimes.
Attached right above within the embedded Tweet courtesy of Mathew Barlow, you can see how the recent behavior and overall evolution of the Polar Vortex circulation was incredibly fluid and very dynamic in nature. Moreover, you can see how when the Polar Vortex circulation finally broke up and pivoted around each other via the “Fujiwara Effect” which can be found in other recent articles which have been posted to our website in recent days (and can also be found through the search tab on the home page of our website), there was still a good portion of the circulation which remained entrenched up within the outer limits of northern Canada and the Arctic Circle. Thus, even as severely cold as it ended up getting within the past 7 to 10 days across the north-central and northeastern United States, there were still other “pieces of the puzzle” which never quite made it down into the United States which is good news despite how frigid it still was for a solid 3 to 4-day period not too long ago.
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© 2019 Meteorologist Jordan Rabinowitz