Polar Vortex Triggers Winter Storms in US

January 7, 2025

The United States is currently facing severe winter storms, impacting over 60 million people in the eastern regions. This cold spell is expected to bring temperatures as low as -50°C (-60°F). The cause is the polar vortex, a mass of extremely cold air that has expanded southwards from the Arctic. This phenomenon predominantly affects areas in the Northern Hemisphere, especially those at mid to high latitudes, leading to extreme cold weather events.

What is the Polar Vortex?

The polar vortex is a large area of low pressure and cold air surrounding the Earth’s poles. It spins anticlockwise around the North Pole, with wind speeds reaching approximately 155 mph (250 km/h). There are two main types of polar vortexes – tropospheric and stratospheric. The tropospheric vortex exists in the lowest layer of the atmosphere, influencing most weather patterns.

Types of Polar Vortexes

The stratospheric polar vortex forms higher in the atmosphere, typically 10-30 miles (16-48 km) above the Earth’s surface. This vortex develops in autumn and dissipates in spring. When stable, it confines cold Arctic air to polar regions. However, if weakened, it allows frigid winds to extend southward, affecting areas as far as Florida.

Factors Affecting the Polar Vortex

The polar vortex can weaken due to rising warm air from lower atmospheric layers. This warm air can be caused by weather patterns or climate phenomena, such as strong winds in mountainous regions or shifts in tropical climates. Both types of polar vortexes play crucial roles in global atmospheric circulation and climate regulation.

Frequency of Polar Vortex Events

Cold polar vortex events are seasonal but not guaranteed every year. The term “polar vortex” gained popularity after the severe winter of 2013-14, which brought record low temperatures and snowfall across Canada and the eastern United States. Major cities like New York, Philadelphia, and Chicago experienced some of the highest snow accumulations in their histories.

Historical Impact of the Polar Vortex

The 2013-14 polar vortex led to 92.5 percent of the Great Lakes being frozen over, the second most extensive ice cover recorded. Lake Michigan experienced an unprecedented 93.3 percent ice coverage on March 8, 2014. The polar vortex became widely discussed in media, solidifying its place in public understanding of winter weather patterns.

Climate Change and the Polar Vortex

Researchers are examining how climate change influences the polar vortex’s intensity and frequency. Some evidence suggests that global warming may weaken the polar vortex. As the North Pole warms faster than other regions, the temperature difference between polar and mid-latitude areas decreases. This change destabilises the polar jet stream, allowing polar air to move further south into Europe and North Asia.

The polar vortex was not a common term until 2014.
The 2013-14 polar vortex caused record ice coverage on the Great Lakes.
Lake Michigan had its highest ice coverage ever recorded at 93.3%.
The polar vortex spins at wind speeds of about 155 mph.
Climate change may weaken the polar vortex by reducing temperature differences.

About Atmospheric Circulation

The polar vortex is integral to global atmospheric circulation. It influences weather patterns and climate regulation across the Northern Hemisphere. About its dynamics helps in predicting severe weather events and their impacts on various regions.

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