In the midst of a record cold wave of over 50 degrees below zero in the United States ahead of Christmas, experts analyzed the cause of the severe cold as 'extreme vortex'.
The New York Times reported that the cold and dry atmosphere from the North Pole recently descended to the American continent, causing the perceived temperature to drop to -53 degrees Celsius in Chicago and -54 degrees Celsius in Memphis, Tennessee the previous day.
This cold wave is expected to be accompanied by a blizzard, and it is expected that there will be chaos, such as flight cancellations one after another ahead of the peak travel season from Christmas to New Year.
The reason why the strong cold wave shut up in the United States is because the 'polar vortex', a mass of cold and dry air that revolves around the North Pole, moved south to the American continent.
The Arctic Polar Vortex is strongest and cools during the winter months when little sunlight reaches the North Pole.
The polar vortex is generally trapped in the jet stream, a strong westerly wind blowing from the upper troposphere, and cannot move south and stays around the North Pole. A cold will hit your back.
If the movement of the polar vortex, which should be in the North Pole, accelerates like this, the temperature in the area exposed to the cold air of the polar vortex will drop by several tens of degrees within a few hours.
Experts feared that these extreme weather events could continue for up to several weeks, until the polar vortex returned to its original position and stabilized.
However, there is no consensus in the scientific community as to why this phenomenon occurs.
University of Wisconsin climate scientist Dr. Steve Barbrus proposed a hypothesis in 2012 that Arctic warming might affect the path of polar vortices, but "the situation is still ambiguous," he said.
Dr. Judah Cohen of the Atmospheric Environment Institute in Lexington, Massachusetts, USA, said that large and strong atmospheric waves are formed in warm environments, and the warming of the Arctic caused the jet stream wave to ripple with a larger width than under normal conditions, which also had a cascading effect on the polar vortex. Thesis was published this year.
However, researchers at the University of Exeter in the UK, in a paper published in the journal Nature Climate Change in 2020, found that short-term trends in climate-related measurements, such as cold extremes and jet stream waveforms observed in the 1990s and 2000s, have not been consistent over the past decade. .
In addition, Ted Shepard of the University of Reading in the UK has proposed another hypothesis that sea surface temperatures in the tropical Pacific Ocean may affect the Arctic air masses that disrupt the jet stream and polar vortices, to find a correlation between Arctic warming and the jet stream. Opinion that it is difficult is still a situation.
(Photo = AP, Yonhap News)