A large-scale, persistent low-pressure circulation near Earth’s poles is called a polar vortex.
Polar vortices are broad regions of cold, rotating air surrounding the Arctic and Antarctic. The term covers two related but distinct systems: the tropospheric vortex, extending from near the surface toward the tropopause, and the stratospheric vortex, found roughly 15 to 50 kilometers above Earth and strongest during winter.
The winter vortex develops as polar darkness allows the region to cool sharply. The resulting temperature contrast between the pole and lower latitudes supports powerful west-to-east winds, while the Coriolis effect organizes them into a circulation. It weakens in spring as sunlight returns and the polar stratosphere warms.
A polar vortex is not a single storm that automatically brings cold weather to every nearby region. When it is disturbed or displaced, the jet stream can shift and cold polar air may spill toward lower latitudes. This is why news reports often connect a weakened vortex with cold outbreaks, even though the vortex itself remains high above much of the weather people experience.