The United States is witnessing severe winter storms that are likely to affect more than 60 million people in the east of the country. The persistent cold snap, which could see the mercury drop to -50 C (-60 F), is caused by the polar vortex – an extremely cold region, orbiting the North Pole – expanding southward.

Low to freezing temperatures could extend as far south as the Gulf Coast and the Florida Peninsula in the United States.

The polar vortex primarily affects countries located in the middle and high latitudes of the Northern Hemisphere. These areas are particularly vulnerable to extreme cold weather events.

What is a polar vortex?

The polar vortex rotates counterclockwise around the North Pole with wind speeds of about 155 mph (250 km/h).

There are two types of polar vortexes – the troposphere and the stratosphere.

The tropospheric polar vortex occurs in the lower layer of the atmosphere where most weather phenomena occur. The vortex creates milder weather across northern latitudes.

The polar vortex we are currently experiencing is a stratospheric polar vortex that typically occurs about 10-30 miles (16-48 km) above the Earth’s surface and forms in the fall but disappears in the spring of each year.

When the stratospheric polar vortex is in a steady state, frigid Arctic air is confined to the polar regions.

But when in a weakened state, cold winds expand beyond the circumpolar Arctic and extend as far south as Florida.

Warm air rising from the lower atmosphere weakens the polar vortex, allowing it to spread more widely. This upward movement of warm air can result from large weather patterns or phenomena, such as strong winds in mountainous regions or changes in tropical climate systems.

Both types of polar vortexes are important for global atmospheric circulation and climate regulation.

Do we experience cold polar vortexes all the time?

The extremely cold temperatures caused by a weak polar vortex, although seasonal and cyclical in nature, are not an annual phenomenon. In fact, it wasn’t until 2014 that the term polar vortex became a common colloquial term.

The 2013-2014 polar vortex brought record snowfall and cold across Canada and the eastern United States, plunging the regions into one of their coldest winters.

Major metropolitan areas, including New York, Philadelphia and Chicago, were blanketed in snow, with accumulations ranking among the 10 highest in their recorded history.

According to a 2015 NASA article, the 2013-2014 polar vortex resulted in 92.5% of the Great Lakes being covered in ice, the second largest ice cap ever observed via satellite. Lake Michigan’s surface froze to an unprecedented 93.3% on March 8, 2014, representing the highest ice coverage ever recorded for this great lake.

In 2014, many news agencies and weather reports widely discussed this weather pattern, making it a household name. Not only did extreme cold capture public attention, it also provided a widely available explanation for extreme weather conditions, cementing the polar vortex within the cultural zeitgeist as a key factor in understanding winter weather patterns in the Northern Hemisphere.

Does climate change affect the polar vortex?

Researchers are trying to understand the impact of climate change on the intensity or frequency of cold temperatures due to the polar vortex. Some data suggests that climate change may affect the polar vortex.

“It stands to reason that the polar vortex tends not to be as strong due to global warming because the planet is not warming uniformly. “It warms more at the pole, which generally reduces the strength of the polar vortex and the jet stream and makes it more likely to be displaced and sent into our way,” says Steven Decker, director of the undergraduate program in meteorology at Rutgers University. He said Last February.

Global warming makes the polar vortex weaker because the Earth’s temperature is not rising the same amount everywhere. The Arctic is warming faster than other places, weakening the polar vortex and the jet stream – a fast-moving current of air in the atmosphere. This makes it easier for the vortex to pop out and bring cold air to many regions, including Europe and northern Asia.

“This change warms the high latitudes and reduces the temperature difference between warmer mid-latitude regions and the polar regions,” Paul Ulrich, associate professor of regional climate modeling at UC Davis, wrote in a 2021 study. “Weakening and destabilizing the polar jet stream, causing it to retreat to lower latitudes, pushing polar air farther south.” condition.