Polar Vortex, much like bombogenesis, has gotten a reputation of being a social media buzzword despite having an origin long before social media. After gaining popularity over the last decade to describe bouts of extreme cold, the term has often been misused.
In its simplest form, the polar vortex is a broad area of low pressure that circulates across earth's poles at the upper levels. There are two polar vortices on earth: one in the Arctic and one in the Antarctic. Both of these vortices are present year-round, but become more pronounced during the winter months.
The term polar vortex can be traced back nearly 100 years. The term is believed to have been first used in a magazine called 'Living Age' published by Eliakim Littell. The term was published in 1853 in volume 39, page 430 in an article titled "Air Maps." This magazine was published from 1844 to 1941.
The term began to become more popular in the weather circle in the 1940s and 1950s. Multiple academic studies have been published in the last few decades regarding this phenomenon. The term went viral in 2014, making it a much more common phrase in the last decade.
Below: A portion of the Living Age article where the term polar vortex is published for the first time:
Going back to what exactly the polar vortex is and how it affects the weather, the vortex is a large swirling area of cold wind (hence the term vortex) that is typically parked over the Arctic. When the winds of this system are strong, it spins in a tight, circular motion, containing the coldest temperatures to the Arctic. When these winds weaken, it can be pushed off the North Pole and break into two pieces. This can cause arctic air to push southward if other conditions are right.
The polar vortex and polar jet streams are two separate entities that do not directly interact with each other. The jet stream is located 5-10 miles above the surface while the polar vortex spins anywhere from 10-30 miles above the surface. The polar jet stream plays a much larger role in daily winter weather than the polar vortex. When the polar vortex becomes weakened, the polar jet stream will sometimes mirror this disruption, helping to bring extremely cold air farther south, while drawing warmer air into the Arctic.
It's that mirroring effect with the jet stream that allows the extremely cold air of a weaker polar vortex to get farther south. Whether the polar vortex is stronger or weaker can be determined by looking at Arctic Oscillation (AO). When Arctic Oscillation is positive, it indicates a stronger vortex while a negative phase can indicate a weaker one. Just because the vortex is weaker and AO is negative doesn't automatically mean a significant blast of arctic air is coming. The polar jet stream, again, plays a larger role in this than the vortex.
With the increased popularity of the term polar vortex comes the misuse of the term. Calling any shot of very cold air over the United States a polar vortex is not accurate. The polar vortex can play a role in cold shots, but the cold shot itself shouldn't be described as one. Not all cold shots come as a result of the polar vortex. More often than not, it's other factors that directly cause these blasts of Arctic air. When the polar vortex does influence a cold blast, it's just that: an influence, not the vortex itself coming down to the US.
The polar vortex itself is located far above the surface. While it can support extremely cold air at the surface, the actual vortex itself cannot reach the ground, and will never come close to the ground. As we've gone over already, the polar vortex is not a new phenomenon. It has always been present and has been studied for over 100 years.
The polar vortex is always present and shouldn't be thought of as a polar vortex when it affects the weather farther south. There are only two polar vortices across the earth, and only one that affects the United States. While the polar vortex can temporarily break into two pieces, there are not many of them around and they do not form anywhere on earth. It should be thought of as the polar vortex, not a polar vortex.
So, in its simplest terms, the polar vortex IS an area of low pressure that constantly swirls (albeit at varying strengths) high above the north and south poles. The polar vortex ISN'T a storm that brings extreme winter weather to the United States. The polar vortex ISN'T something that will ever be truly felt at the surface, only its influence can be felt at the surface.
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