The polar vortex is a large, persistent low-pressure area of atmospheric circulation that surrounds the Earth's poles. It is characterized by strong, fast winds and cold air masses, forming part of the overall stratospheric circulation pattern. The stability and strength of the vortex are governed by global temperature gradients and atmospheric momentum, essentially acting as a dynamic barrier that typically keeps frigid polar air confined near the poles. When the vortex weakens or is disrupted, usually due to changes in upper-level jet stream patterns, large sections of cold air can become displaced southward or eastward, leading to regional dips in temperature outside of the polar region.