Soon the Spaniards may not be the only ones shivering. Sudden atmospheric warming in the North Pole region has disrupted the flow of winds, threatening to bring to our latitudes the freezing air normally centered around the Pole.
The phenomenon has nothing to do with the Filomena storm, which has just hit central Spain, paralyzing its capital Madrid and killing four people. But it could lead to similar consequences, with falling temperatures and heavy snowfall. Meteorologists are currently not sure that this will happen, but all the conditions seem to be right. Between mid-December and early January, the temperature of the stratosphere in the North Pole region fell from -70 ° C to -20 ° C: a warming of around 50 ° C which caused a reversal of the winds at the within the polar vortex. Normally rotating counterclockwise, they have been facing east since the start of the week. This is what meteorologists call a “sudden stratospheric warming” or SSW (sudden stratospheric warming).
In normal times, the temperature difference between the polar zone plunged in darkness and the regions further south generates a powerful jet stream. These westerly winds form a kind of barrier that prevents the polar vortex, a vortex of freezing air centered on the pole, from descending further south. But when the temperatures of the stratosphere in this area increase, the force of the winds also decreases, sometimes to the point of reversing. Nothing retains the cold air, which can then mix with the jet stream to descend to our latitudes. In other words, the freezer door is open.
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Still many uncertainties
SSWs are far from rare. The last dates back to 2018: in February-March, Europe then experienced an intense cold snap. It had even snowed in Rome. For now, there is nothing to indicate in which direction the polar vortex of 2021 will go, or even if it will not burst into several into several pieces that could drift towards Europe or North America. North. Meteorologists are closely following its development.
However, we do not know why the stratosphere has warmed to this point around the pole, even if some scientists are putting forward leads. For US meteorologist Judah Cohen, director of seasonal forecasts at the Massachusetts Institute of Atmospheric and Environmental Research, interviewed by the LiveScience site, the phenomenon could be linked to the reduction of the sea ice surface.
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