UPSC Express

About Polar Vortex

Normal Condition

• Polar vortex is a low-pressure system where strong cold air masses circulate in counter-clockwise direction, 2 meters over the poles (both North and South).
• Usually the upper cold air mass is trapped in the poles due to existence of low-pressure belt at the poles.(See figure)

Distorted Condition

• Sometimes during the winter, this system is distorted resulting in the cold upper air mass being pushed farther south than usual.
• When distorted, the polar vortex will expand, sending weakened cold air southward with the jet stream.
• In 2014 polar vortex distortion occurred twice, once throughout the winter months and also in early spring.

What is causing the distortion in Polar Vortex?

• The Polar vortex weakens, partly due to warming temperatures in the stratosphere.
• According to recent studies, with the warming of planet the jet stream over North America and Europe, is slowing and becoming wavier.
• The jet streams interact with the polar vortex pushing the cold air downwards south.

Global Warming and Polar Vortex

• It is well known that global warming is leading to melting of Arctic ice.
• During summers as the ice retreats, specific heat is absorbed by the ocean that lies under the ice.
• During winter this heat is released as latent heat into the atmosphere creating high pressure belts in the arctic, spurring winds that can disrupt the polar vortex.
• Thus, global warming is also a cause for cold spans from distorted polar vortex.