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The polar vortex explained


January usually brings the coldest air of the season to much of the country, and this year has seen its fair share.

What do you want to know

  • A polar vortex is not always responsible for the cold
  • The polar jet stream is more responsible for daily weather fluctuations
  • Satellites can recognize a polar vortex event before the cold arrives
  • Climate change could reinforce polar vortex events

Every time this mercury dips, the term “polar vortex” is thrown around and inserted into conversations.

But what is this phenomenon, and is it the reason for this month’s cold snap?

The polar vortex is an area of ​​rapidly moving westerly winds about 10 to 30 miles above the North Pole in the stratosphere.

Inside this zone of winds, there is freezing air on the surface which generally parks around the pole for the winter. However, every few years these fast westerly winds weaken. The protective barrier around cold air breaks down, allowing warmer air to move north in the polar region and cold air to be pushed south in mid-latitudes – places like United States.

This cold air can be in mid-latitudes for an extended period.

February 2021

Do you remember the extreme cold that happened in February 2021? It was because of the polar vortex.

Several weeks before the arrival of the cold in the United States, satellites followed the warming of the stratosphere, showing the weakening of the vortex.

This cold air penetrated as far south as Mexico and broke records across the United States in February. Parts of Texas recorded their lowest readings in more than 100 years, and with that cold came immense strain on the power grid.

January 2022

January 2022 saw cool days, but these cold conditions differ from a polar vortex event.

The reason for the flip-flop in temperatures this month across much of the country has less to do with the polar vortex than with the polar jet stream.

The polar jet stream is an area of ​​fast winds that occur in the troposphere, the level of the atmosphere about 5 to 9 miles above the surface (below the stratosphere).

This boundary separates warm mid-latitude air from colder polar air. The jet stream is more fluid and oscillates during the winter, which is why we see the fluctuations in our weather from day to day. It can be cold for a day or two, but then the temperatures moderate.

Climate change

Climate change usually indicates a warming world; however, a warming world could strengthen the polar vortex, pushing cooler air south.

Associate Professor Paul Ulrich of Regional Climate Modeling at UC Davis explains that it was this warming that melted the Arctic sea ice, altering the albedo in this region and “transforming a highly reflective icy surface into an absorptive surface. dark”.

With a warming Arctic region, more extreme and unusual weather conditions are within the realm of possibility.