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What is a Polar Vortex?

Polar Vortex

As many people across states in the US Midwest and East Coast face severe snowstorms, made worse by freezing winds blowing down in a Polar Vortex, we help you understand this extreme weather phenomenon.

What is a Polar Vortex?
A vortex, as the name suggests, is a rapidly rotating current, in this case of air, very cold air, as it's coming all the way down from the North Pole.
A Polar Vortex usually consists of a dense current of cold air that blows around the North Pole in a counterclockwise direction, well above the surface of the earth. It is a polar weather system that consists of upper-level winds causing an area of low pressure. Because the winds blow in a circular manner they remain in the northern Polar region.

Why has the Polar Vortex come down to the US this year?

At times the circumpolar winds can become distorted and start moving southwards. Thus, cold currents of air start affecting regions that do not usually experience such extremely cold temperatures.

How often does a Polar Vortex move out of its usual range?
As the upper-level air currents rotate, they can lose speed and cause the vortex to change its shape. This distortion in the vortex can cause it to move out of its usual zone and form a jet stream that brings cold air to more southern regions. Also known as Arctic Oscillation, this shift from positive phases (when the cold winds remain in the Arctic zone) to negative phases (when the cold winds affect other regions) can happen several times a year in different regions. The cold winds could affect Asia, Europe, or North America, any part of the northern hemisphere that can be reached by Polar winds blowing southward.

Is a Polar Vortex as dangerous as a Hurricane or Tornado?
A Polar Vortex is a much wider weather system and usually affects a larger region over a longer period of time. When the cold air front meets local warmer air fronts this can lead to the formation of localized winter storms. The intense chill caused by the Polar Vortex is not to be taken lightly however, as the sudden drops in temperature and almost Arctic conditions can cause hypothermia and frostbite if people aren't careful and take adequate precautions against the inclement weather.

How do I protect myself if a Polar Vortex affects where I live?

Follow sensible precautions to fight the intense cold. Stay indoors, stock up on food and water, and ensure your home has adequate heating and insulation. Do not go outdoors unless absolutely necessary. If you do have to go outdoors ensure your vehicle can negotiate the snowbound streets. Preferably do not go out alone or without communications equipment in case you get caught in a snowdrift.

When was the last time a Polar Vortex came southwards?
Cold fronts moving down from the North Pole are not uncommon and cause cold snaps in different regions of the northern hemisphere. In 2012 many part of Europe faced a severe winter because a Polar Vortex affected northern Europe.

While North America has faced intense cold, Europe has seen severe storms recently. Are these episodes of bad weather related?
The wind patterns in the northern hemisphere are such that the jet stream near Ireland and the UK has resulted in many storms across Britain and north-western Europe. As the cold front from the Arctic collides with moist air from the Atlantic, cold Arctic winds have spiraled across North America, while moist Atlantic winds have moved across the coast of northern Europe bringing heavy rain, storm surges and flooding to some areas.

Is the Polar Vortex a consequence of Global Warming?

Meteorologists are analyzing global weather patterns to understand this. It is possible that extreme weather events such as a Polar Vortex could be caused due to excessive melting of Arctic Ice, followed by evaporation from the northern seas, and dense moisture-laden cold winds circulating in a distorted manner. The cold front that has moved over North America could be a consequence of this related weather pattern.

Last Updated : January 08, 2014