Understanding the Polar Vortex and Its Impact on Winter Weather

What is the Polar Vortex?

The United States is currently facing severe winter storms affecting over 60 million people in the eastern part of the country. Temperatures could plunge to -50°C (-60°F) due to the polar vortex, a massive area of cold, rotating air around the Arctic that has expanded southwards.

This weather phenomenon primarily influences mid to high latitude regions in the Northern Hemisphere, occasionally bringing sub-freezing temperatures as far south as the Gulf Coast and Florida Peninsula.

The polar vortex rotates counterclockwise around the North Pole with wind speeds of approximately 250 km/h (155 mph). It has two forms: the tropospheric polar vortex, located in the lowest atmospheric layer where most weather events occur, and the stratospheric polar vortex, situated 16-48 km (10-30 miles) above Earth's surface. The stratospheric vortex forms in autumn and typically dissipates by spring.

In a stable state, the stratospheric polar vortex keeps cold Arctic air confined to polar regions. However, when weakened, warm air from the lower atmosphere disrupts its stability, causing the cold air to spread southward. Weather patterns, such as strong winds over mountains or shifts in tropical systems, often trigger this destabilization.

Not a Constant Phenomenon

While the polar vortex plays a crucial role in global climate regulation, its extreme cold effects are not annual. The term gained public recognition in 2014, following record-breaking cold and snowstorms during the 2013-14 winter. That season saw significant snowfall in major U.S. cities and extensive ice coverage on the Great Lakes, with Lake Michigan experiencing its highest recorded ice extent.

Climate Change and the Polar Vortex

Researchers are investigating the relationship between climate change and the polar vortex. Data suggests that global warming weakens the polar vortex by reducing the temperature contrast between the polar and mid-latitude regions. This destabilization increases the likelihood of the polar vortex expanding southward, bringing cold Arctic air to lower latitudes.

As the planet warms unevenly, with the Arctic experiencing more rapid heating, the polar vortex and jet stream become less stable. This phenomenon contributes to erratic winter weather patterns, affecting regions in North America, Europe, and Asia.