In recent times, a meteorological phenomenon called a polar vortex has started generating much attention due to its devastating effects on countries in the Northern Hemisphere. We take a closer look at this event.

The name polar vortex surfaces in the mainstream media every once in a while. Usually this happens when it “misbehaves” and reaches further south than it is supposed to, and impacts the lives of millions of people in countries in the Northern Hemisphere.

We first have to quickly clear up the misconception that a polar vortex itself is the problem or abnormal in any way. We will address this issue and also go into detail explaining why and when it becomes dangerous.

Before getting into further detail about how a polar vortex works and how it impacts the environment, one first has to describe what precisely this meteorological phenomenon is: 

Polar Vortex Definition​​​​​​​​​

A polar vortex is defined as a large area of low pressure and cold air centred above each of the Earth’s poles. In the Northern Hemisphere, the stratospheric polar vortex is most prominent during winter and extends roughly 11 to 50 kilometres above the Arctic. Its air rotates counterclockwise and can reach temperatures as low as -80° Celsius.

In the Northern Hemisphere, the stratospheric polar vortex is a large low-pressure system that develops in the mid-to-upper atmosphere above the Arctic during winter and extends from around 11–50 kilometres (7–31 miles) in altitude.

It rotates counterclockwise above the polar region and is characterised by freezing temperatures as low as -80° Celsius (-112° Fahrenheit). Strong winds circulate around the vortex and help to contain the cold air above the Arctic.

At a lower altitude, the Polar Front Jet Stream flows around the Northern Hemisphere along the boundary between cold polar air and warmer air farther south. These strong winds can reach speeds in excess of 257 km/h (160 mph). When the jet stream remains strong and stable, it generally helps to keep the cold Arctic air farther north.

It is very important to understand that the polar vortex itself is a normal phenomenon that develops above the Arctic during winter. As long as the vortex remains strong and stable and doesn’t lose its shape, the coldest air generally remains confined to the polar region and poses little danger to regions farther south.

Simply put, a strong polar vortex is a safe polar vortex.

Now that we have established what a normal polar vortex is, we need to examine when and how it starts to “misbehave” and threaten regions further to the south.

Usually, a strong polar vortex helps the Polar Front Jet Stream to remain strong and maintain its normal shape. The jet stream also forms the boundary between the cold polar air and the warmer air farther south.

With air temperatures within the polar vortex reaching -80° Celsius (-112° Fahrenheit) in the mid-upper atmosphere, the maintenance of a strong boundary between the Arctic and subtropical air is essential.

It is when the low-pressure system in the polar vortex starts to weaken that an unstable environment is created.

There are a variety of ways in which the vortex can weaken (which we will discuss later in the article), but it is usually the presence of warmer temperatures that disrupts the strong low-pressure system that holds the polar vortex together.

When the warmer air mixes with cold Arctic air, the low-pressure system starts to weaken substantially. This has a direct effect on the Polar Front Jet Stream surrounding it.

The strength of the jet stream relies on the strength of the temperature difference between the cold Arctic and subtropical air. The warmer air in the Arctic causes this difference in air temperatures to weaken.

As a result, the jet stream weakens and starts to lose its normal shape and structure. It begins to wind and flow in a more wavy manner, causing its borders to reach much further south than usual.

The weakened low-pressure system and a compromised jet stream can even cause the polar vortex to split, where the primary vortex is broken down into smaller vortices, and each piece can move in a different direction. When this allows Arctic air to move much farther south, it is commonly referred to as a polar outbreak.

Regions that would typically not be affected under stable conditions are now directly exposed to Arctic air and temperatures. In some cases, these regions may even become colder than parts of the Arctic itself for a short period.

And this is the real danger of a polar vortex. When a vortex weakens, the Polar Front Jet Stream weakens and loses its shape, causing its wavy border to wander far south and affect areas that would normally not be exposed to this phenomenon at all.

Simply put, a weak polar vortex is an unstable and dangerous polar vortex.

Now that one knows why a polar vortex can become so dangerous and that temperature plays a major role in weakening it, we need to establish what causes these disturbances in temperature.

Meteorologists are not completely sure themselves and are still debating the underlying causes that may lead to these dangerous polar outbreaks.

There are quite a few viable explanations, though, some of which have already been proven.

An accelerated rise in temperatures over the last couple of decades globally has already been recorded and confirmed. (No, this is not an argument for or against climate change. It is simply a statement of the facts.)

In the Arctic Region, the situation is even worse. Surface temperatures in this area have been warming around three to four times faster than the global average.

The melting of snow cover and sea ice is mainly responsible for this accelerated warming of air temperatures in the polar regions. The white snow and ice usually reflect the majority of heat from the sun. The darker waters of the ocean, in contrast, absorb and retain the heat.

With less ice and snow present, more heat gets absorbed and retained by the exposed ocean water. The resulting warmer air, combined with global warming, leads to this accelerated rise in temperature, which is known as Arctic Amplification.

This phenomenon causes the warmer air over the Arctic to move in from the sides of the polar vortex and disrupt the cold air. This causes the weakening of the vortex and deformation of the jet stream, as I described in the previous section.

As the polar vortex becomes more severely disrupted, Arctic Amplification can cause the vortex to split into multiple vortices. This can allow Arctic air to move much farther south, leading to a polar outbreak.

And, as already discussed, it is the movement of these multiple vortices that can cause the polar jet stream to veer seriously off course and reach areas much further south.

One can argue that Arctic Amplification is a direct result of global warming. This implies that, indirectly, climate change is responsible for the weaker polar vortex, whose deformed shape causes it to venture south and impact countries in the Northern Hemisphere.

It leaves the question of whether Climate Change can be more directly linked to a polar vortex. To be honest, no direct link or specific body of evidence between Climate Change (global warming) and “wandering” polar vortices has been established yet.

Scientists and meteorologists have bits and pieces of evidence that point to a more direct correlation between the two, but more research and data gathering need to be done before something concrete can be deduced and a conclusion reached.

Once the polar jet stream gets disrupted to the point where it loses its shape and takes on a wavy form, regions not used to the extreme cold now get exposed to Arctic temperatures with potentially fatal consequences.

I am not sure anyone who hasn’t experienced the full brunt of a polar vortex can fully grasp the severity and danger that accompanies this phenomenon.

An extreme example of a polar vortex engulfing and trapping huge parts of the United States of America in January 2019 can be used as a perfect example of just how bad things can get.

Cities and towns in Minnesota experienced some of the most extreme cold weather in history, which is a direct result of the polar vortex. Looking at the conditions they were exposed to and the resulting consequences will help to shine some light on the dangers of such an event.

In Cotton, Northern Minnesota, temperatures dropped as low as -49° Celsius (-56° Fahrenheit). Chicago wasn’t too far behind Cotton, with temperatures reaching lows of -31° Celsius (-23° Fahrenheit).

These temperatures were colder than those experienced at the North Pole and Antarctica during the same period! This is enough to cause severe health issues within minutes.

People were advised to stay indoors, schools were closed, flights were canceled, and the USPS canceled mail deliveries during this period. And with good reason.

These are some of the dangerous conditions and health risks that existed during this period.

Dangerous Transport And Infrastructure Conditions

Roads were instantly iced over, especially with black ice, making them extremely slippery and dangerous to drive on.

Open-flame heaters were used alongside sections of the railway tracks to prevent the switches from freezing and keep trains running safely.

The accompanying snowfall on roads and railways in many areas made travel almost impossible, and commuters got stuck on roads across the country.

Hypothermia

In subzero temperatures, it can only take minutes for one’s core body temperature to drop to dangerously low levels. In the extreme cold of a polar vortex, this process is accelerated.

If not treated immediately, this condition is normally deadly, and quite a few fatalities were recorded during this period in the coldest states.

Frostbite

Frostbite occurs when one’s skin is exposed to freezing temperatures, especially those as low as those experienced during a polar vortex.

It can happen very quickly to exposed skin under these extreme conditions, sometimes after only five minutes of exposure.

Frostbite leads to the skin and underlying tissue dying. In the severe conditions of a polar vortex, prolonged exposure can even lead to the loss of digits and limbs.

These are just a few of the many dangers that accompany a polar vortex when a region is exposed to its full force.

Now that one has a good idea of exactly what a polar vortex is and what causes it to become dangerous, one will be able to better understand such an event.

One will also have a better understanding of the conditions that normally accompany this phenomenon and how dangerous it can get.

Although polar-vortex disruptions and severe cold outbreaks will continue to occur, there is currently no clear evidence that they are becoming more frequent. Even so, this remains a condition that affected regions need to be prepared for during winter.

Until next time, keep your eye on the weather!