Explanation:

The polar vortex is a large area of cold air and low pressure surrounding both the poles of the Earth. • The polar vortex is located high in the stratosphere. • A whirling mass of cold air circulates in the counter- clockwise direction (west to east) called Jet Stream. • The jet streams keep the polar vortex closer to the poles. • It always exists near the poles, but weakens in summer and strengthens in winter. 

• Strong Jet Stream (In case of North Pole) – The Jet stream which surrounds the polar vortex, acts as a barrier between the cold air in the north, and the warmer air in the south. • Weak Jet Stream (In case of North Pole) - As the polar vortex weakens, jet stream begins to undulate and take on a more oval shape, bringing more cold air southward. The band of air then meanders in such a way that it allows cold air from the north to intrude at lower latitudes, particularly over the eastern United States. Learning: Experts are taking a closer look at the link between the winter storms and climate change. • Effects of Weak polar vortex - When the polar vortex becomes perturbed or disrupted, there is an increase in the probability of severe winter weather. • According to a 2021 study, this type of disturbance is occurring more often, and is reflected lower in the atmosphere and the jet stream. • Other effects are - The Lake-effect snow in the Great Lakes region, Bomb cyclone and Stratospheric warming. • Reason for increased disturbances - The changes in the Arctic, accelerated by climate change, the rapid melting of sea ice, and an increase in snow cover in Siberia