Why in the News?

The United States is facing severe winter storms as the polar vortex is expanding southward from the Arctic and driving temperatures as low as -50°C (-60°F).

What is a Polar Vortex?

• The polar vortex is a band of fast-moving air that traps cold Arctic air within the Polar Regions.
• It is a natural atmospheric phenomenon, typically spinning in a counter-clockwise direction around the North Pole.
• Wind speeds in the polar vortex can reach up to 250 km/h (155 mph).
• Causes of a Polar Vortex:

1. Stable State: Under normal conditions, the polar vortex remains strong and well-contained within the Arctic Circle, keeping frigid air confined to the Polar Regions.
2. Weakened State:

• The vortex weakens when rising warm air from the lower atmosphere disrupts its circular flow, allowing Arctic air to spill southward.
• Factors contributing to a weakened state include: Significant weather patterns (e.g., powerful winds in mountainous regions); Changes in tropical climate systems or sea surface temperatures. Climate change causing uneven warming, especially at the poles..

What are its types?

1. Tropospheric Polar Vortex:

• It occurs in the lowest atmospheric layer (troposphere) where most weather phenomena take place.
• Typically results in milder weather across northern latitudes.

1. Stratospheric Polar Vortex:

• Forms 16–48 km above the Earth’s surface in the Stratosphere.
• Stronger and more stable but can weaken due to disruptions, leading to southward extensions of Arctic air.
• It emerges in autumn and dissipates by spring each year.

Impacts of a Polar Vortex

• Extreme cold temperatures in mid-latitudes.
• Prolonged cold spells can disrupt daily life and strain infrastructure.
• Increased snowfall in regions like the eastern U.S., Canada, and parts of Europe.
• Historical Example: In 2013–14, the polar vortex caused record-breaking snowfall and 93.3% ice coverage on Lake Michigan.
• Frost damage to crops, particularly in regions unaccustomed to extreme cold; Delays in planting or harvesting.

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