Parts of America are colder than Antarctica! This was the headline in major journals worldwide and surely has been the hot (or should I say cold) topic discussed & debated amongst environmentalists and people across the globe recently. The conditions were certainly quite harsh in a few areas of the USA. The temperature has been recorded as low as -40° Celsius; said to be the lowest the mercury has dipped since several decades. The reason for this sudden sweep of cold winds is attributed to 'Polar vortex'.
What is this Polar Vortex? Is it some newly coined term or it has always existed? Has the temperature ever been so low in USA because of it in the past? How long is this to stay? Read on to get the answers to these questions.
What is this Polar Vortex? Is it some newly coined term or it has always existed? Has the temperature ever been so low in USA because of it in the past? How long is this to stay? Read on to get the answers to these questions.
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| Cassini model over Saturn's North Polar Vortex: NASA/JPL-Caltech/SSI/Kevin M. Gill |
What is Polar Vortex?
Before answering the question, let me talk about a few basic terms from Geography. As we all know, Earth is divided into 2 halves by an imaginary line called Equator, running round the planet at 0° latitude. Some other prominent latitudes encircling Earth are 23.5° & 66.5° latitudes, in the northern as well as southern hemisphere. Region above the 60° N latitude is called Arctic region while the one below the 60° S latitude is called the Antarctic region. Similarly, we have North & South poles respectively in the Arctic and Antarctic regions.
Coming to the question, Polar Vortex is basically a large area associated with 'cold air' and 'low pressure'. The cold air stream moves in counter clockwise direction at North pole, while at South pole, it moves in Clockwise direction to align with Coriolis effect. Because of the presence at poles, the name 'polar' is associated & since the movement of air is always towards Eastern direction around the poles, the movement is called 'vortex'. Hence the term Polar Vortex.
Coming to the question, Polar Vortex is basically a large area associated with 'cold air' and 'low pressure'. The cold air stream moves in counter clockwise direction at North pole, while at South pole, it moves in Clockwise direction to align with Coriolis effect. Because of the presence at poles, the name 'polar' is associated & since the movement of air is always towards Eastern direction around the poles, the movement is called 'vortex'. Hence the term Polar Vortex.
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| Polar Vortex captured in Jan. Source: NASA |
How does Polar Vortex result in extreme cold temperatures?
Polar Vortex has a strong jet current that keeps the cold air in check and traps it around the poles. High pressure system originating in Pacific, displaces this ecosystem, & weakens the Polar vortex; at times even dismantles it. Once the system is weaker, the vortex breaks up and the child vortex drifts away from the poles; moving further south hitting the Canadian and American main lands.
The sudden gust of these strong, cold winds brings with itself a harsh winter, dipping mercury to sub-zero temperatures. This is the situation that rocked the American states recently and became an International news. But as you read above, it is these winds that are the reason for the gripping and inhuman cold. In other words, the weakening of Polar Vortex is the culprit for the extreme temperatures and not the Polar Vortex in itself.
A point worth noting is that the Polar Vortex doesn’t become weak that often. Only once in a while it happens, resulting in this hostile climate. Many records were broken by this 2019 US winter. Quite a few parts of MidWest America witnessed coldest winter in two decades while a few areas faced all time low temperatures.
Wisconsin recorded -43° Celsius on Jan. 30, an all-time low for the area. In Cotton, Minnesota, mercury dipped precariously to -56° Celsius on Jan 31.
The sudden gust of these strong, cold winds brings with itself a harsh winter, dipping mercury to sub-zero temperatures. This is the situation that rocked the American states recently and became an International news. But as you read above, it is these winds that are the reason for the gripping and inhuman cold. In other words, the weakening of Polar Vortex is the culprit for the extreme temperatures and not the Polar Vortex in itself.
When did Polar Vortex came into existence?
The Polar Vortex has always been present. It recently gained prominence, much attributed to social media. The earliest record of this cold spell is mentioned in the mid 19th century, circa 1853. The phenomenon gained popularity by the media during the winter of 2014-15 in America. However, the current (January 2019) cold spell brought it fame & recognizance across the world, with likes of Twitter, Facebook, WhatsApp providing the impetus in spreading the word to the mass.A point worth noting is that the Polar Vortex doesn’t become weak that often. Only once in a while it happens, resulting in this hostile climate. Many records were broken by this 2019 US winter. Quite a few parts of MidWest America witnessed coldest winter in two decades while a few areas faced all time low temperatures.
Wisconsin recorded -43° Celsius on Jan. 30, an all-time low for the area. In Cotton, Minnesota, mercury dipped precariously to -56° Celsius on Jan 31.
Nerd notes:
- Air is heaviest at the bottom of atmosphere & as one moves up the surface, it becomes thinner
- Low pressure area forces air within the system while High pressure area drives the air away from the system - Reason for Vortex split
- Not all cold spells in US/Canada are due to weakening of Polar vortex
Thanks for reading and keep smiling !
- Prakhar
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