<h4>Understanding the Polar Vortex</h4><p>The <strong>Polar Vortex</strong> is a large area of low pressure and cold air surrounding both of the Earth's poles. It always exists, but usually stays contained within the polar regions.</p><p>The term 'vortex' refers to the counter-clockwise flow of air that helps keep the colder air bottled up at the poles. This phenomenon is more pronounced in the <strong>Northern Hemisphere</strong> during winter.</p><h4>Location and Structure</h4><p>There are actually two main types of polar vortices. The stronger one is located in the <strong>stratosphere</strong>, approximately 10 to 50 km above the Earth's surface. A weaker, larger one exists in the <strong>troposphere</strong>, closer to the ground.</p><div class='info-box'><p>The <strong>stratospheric polar vortex</strong> is a massive, persistent low-pressure system that forms over the poles during winter, characterized by extremely cold temperatures and strong westerly winds.</p></div><h4>Normal Behavior and Stability</h4><p>Normally, the polar vortex is strong and stable. It acts like a barrier, keeping the frigid polar air confined to the Arctic and Antarctic regions. This is largely influenced by the strength and stability of the <strong>jet stream</strong>.</p><div class='key-point-box'><p>A <strong>strong polar vortex</strong> means a more stable, circular flow, effectively trapping cold air at the poles. This leads to milder winters in mid-latitudes.</p></div><h4>Weakening and Destabilization</h4><p>Occasionally, the polar vortex can weaken or become unstable. This often happens due to disturbances in the <strong>jet stream</strong>, which can be influenced by phenomena like <strong>sudden stratospheric warming (SSW)</strong> events.</p><p>When the vortex weakens, it can become elongated or split into multiple lobes. This allows parts of the extremely cold polar air to 'spill out' or migrate southward into mid-latitude regions.</p><h4>Impact on Mid-Latitudes</h4><p>The southward migration of polar air masses leads to significant drops in temperature, often causing severe winter storms, heavy snowfall, and dangerous wind chills in areas not typically accustomed to such extreme cold.</p><div class='exam-tip-box'><p>UPSC often asks about the relationship between <strong>Polar Vortex</strong>, <strong>Jet Streams</strong>, and <strong>Climate Change</strong>. Understanding the 'why' behind its destabilization is crucial for Mains answers.</p></div><h4>Recent Events: The US Winter Storm</h4><p>The recent severe winter storm in the <strong>US</strong>, impacting over <strong>60 million people</strong> across <strong>30 states</strong>, is a prime example of a weakened or disrupted polar vortex event. This brought unusually low temperatures and widespread disruption.</p>