Polar Vortex and Winter Storm in USA

Syllabus: GS1/Geography

Context

• Recently, the United States has experienced one of the most severe winter storms in over a decade, largely attributed to the polar vortex.

About the Polar Vortex

• It is a large area of low-pressure and cold air that swirls around the Earth’s polar regions. 

• It exists in two forms:
  • Tropospheric polar vortex, which occurs in the lowest layer of the atmosphere (up to about 10-15 km), and 
  • Stratospheric polar vortex, which occurs higher up (around 15-50 km).
• The tropospheric polar vortex is responsible for most weather phenomena, while the stratospheric polar vortex is strongest during autumn and disappears in summer.

How Does the Polar Vortex Cause Extreme Cold?

• When the polar vortex is strong and stable, it keeps the jet stream (a narrow band of strong wind in the upper atmosphere) traveling in a circular path around the planet.
  • It helps maintain a separation between cold air in the north and warm air in the south.
• However, when the polar vortex weakens, it can cause the jet stream to become wavy and meandering.
  • It allows cold Arctic air to break off and move southward, bringing frigid temperatures to regions as far south as Florida.

Impacts of the Polar Vortex

• Cold Air Outbreaks: When the polar vortex expands or shifts, it can push Arctic air southward into regions like the USA, Europe, and Asia. This often leads to extreme cold outbreaks in the Northern Hemisphere.
• Ozone Depletion and the Polar Vortex: The polar vortex traps cold air, leading to ozone depletion over Antarctica. Cold temperatures cause harmful chlorine compounds to accumulate, breaking down ozone. This results in the creation of the ozone hole over Antarctica.
• Impact on Aviations: It can impact aviation operations by causing very cold ground temperatures and increased winter precipitation.
• Impact on India: A weakened polar vortex increases western disturbances in India. Western disturbances bring heavy snowfall to the western Himalayas.

Source: IE