What is a polar vortex?

A polar vortex is defined as a large area of low pressure and cold air surrounding the Earth's poles. This phenomenon is characterized by the circulation of cold air masses that are typically found in the stratosphere over the polar regions. The polar vortex can become disrupted, leading to the displacement of cold air towards lower latitudes, which can contribute to extreme winter weather events in midlatitudes.

Understanding the polar vortex is crucial for interpreting weather patterns, especially during winter months. When the polar vortex is strong, it keeps the cold air confined near the poles, while a weaker polar vortex can allow frigid Arctic air to move southward, resulting in significant temperature drops and potentially harsh weather conditions in places that typically experience milder winters.

The other options do not describe the polar vortex accurately. Warm air masses from the tropics, precipitation types, and high-pressure systems over the equator do not pertain to the characteristics or phenomena associated with the polar vortex. This distinction is essential for grasping the complexities of global weather systems and their impacts on regional climates.