Warmer air is invading the stratosphere at the North Pole right now.
The stratosphere is the atmospheric layer that starts at an altitude of around 6 miles. Weather doesn’t occur in the stratosphere. It occurs at the lowest level of the atmosphere known as the troposphere.
Changes in the stratosphere can impact the jet stream in the higher levels of the troposphere. This is an area of high winds that tends to separate warm and cold air.
The stratospheric polar vortex is a large area of cold air rotating counter-clockwise around the North Pole.
It is always there. The lack of sunlight in the winter allows the polar vortex to expand further south every year.
Right now warmer air is developing an area of high pressure near the North Pole that is weakening the polar vortex.
The polar vortex is becoming less stable. In the past when there is a spike of warmer air in the stratosphere, the jet stream in the troposphere will become more active.
Historically this leads to blasts of bitterly cold air in the Northern Hemisphere.
The polar vortex is an area of cold air rotating counter-clockwise. This is also known as an area of low pressure.
The polar vortex is always at the poles. Shorter days during the winter in the northern hemisphere result is colder temperatures with less sunlight. The polar vortex will expand in the winter. Disruptions like high pressure can weaken the jet stream and send colder air further south the usual.
According to the National Oceanic and Atmospheric Administration, the earliest documentation of the term polar vortex was in E. Littell’s Living Age in 1853.