What is a polar vortex? The arctic winds that brought cold air and chaos to the US
Steve Connor is the Science Editor of The Independent. He has won many awards for his journalism, including five-times winner of the prestigious British science writers’ award; the David Perlman Award of the American Geophysical Union; twice commended as specialist journalist of the year in the UK Press Awards; UK health journalist of the year and a special merit award of the European School of Oncology for his investigative journalism. He has a degree in zoology from the University of Oxford and has a special interest in genetics and medical science, human evolution and origins, climate change and the environment.
Monday 06 January 2014
Much of the United States is currently in the grip of a polar vortex, a system of dense air producing plummeting temperatures and swathes of freezing weather, bringing some parts of the country to a halt and causing chaos in others.
A polar vortex is a circulating pattern of strong winds flowing around a low-pressure system, which normally sits over the Arctic during winter. The effect of such a vortex is to keep the cold air circulating within the polar region.
However, when the vortex breaks down or splits into two, it can send very cold air further south.
The weather conditions produced by this polar vortex have been so severe that even polar bears at the Lincoln Park zoo in Chicago were brought inside as the weather dropped to a record low of -26C, CNN have reported. Residents have been warned their skin may freeze if they leave their homes when wind chills plummeted to -53C.
Chicago's National Weather Service office reported that Monday's low of -26C at O'Hare International Airport beat a record set in 1884 and equalled in 1988. In Fargo, the largest city in North Dakota, temperatures sank below - 35C.
A swirling mass of Arctic air moved south into the continental United States. The air mass began breaking off from the polar vortex, a semi-permanent low-pressure system with a center around Canada’s Baffin Island
Forecasters predict 187 million people could feel the effects of the "polar vortex" by the time it spreads across the country. At least 13 people are thought to have died as a result of the extreme conditions already, including several road accidents, a man who succumbed to hypothermia in Wisconsin, and a worker crushed by a massive pile of road salt at a storage facility in Philadelphia.
The weather conditions produced in the polar vortex could also make temperatures drop to the coldest on record in the 21st century. The National Weather Service predicts temperatures will be 25 to 35 degrees below average for the Mid-Atlantic, Southeast to the Ohio, Tennessee Valleys and into the Upper Midwest today.
Some scientists believe that warmer-than-average conditions in the Arctic can weaken the polar vortex, so causing colder-than-average conditions at lower latitudes. They think this could help to explain the extreme conditions of the 2009-2010 winter when the normal pattern of Arctic winds broke down causing a weakened polar vortex to allow a frigid body of air to move south. This brought record snow conditions to northern Europe, eastern Asia and eastern North America.
The polar vortex explained
Polar vortices tend to strengthen in the winter and weaken in the summer and can span a distance of more than 1,200 miles, with the air circulating in an anti-clockwise fashion around the North Pole.
A polar vortex also occurs around Antarctica, and is a key feature of the winter weather of the southern hemisphere that results in the conditions necessary for the depletion of atmospheric ozone.
- 1 Emma Watson on Jennifer Lawrence naked photo leak: 'Even worse than seeing women's privacy violated is reading the comments'
- 2 Saudis risk new Muslim division with proposal to move Mohamed’s tomb
- 3 A teacher speaks out: 'I'm effectively being forced out of a career that I wanted to love'
- 4 Cee Lo Green: It is only rape if the victim is conscious
- 5 Nigerian witch-finder Helen Ukpabio threatens legal action against human rights organisations
Emma Watson on Jennifer Lawrence naked photo leak: 'Even worse than seeing women's privacy violated is reading the comments'
Victoria Justice on naked photo leak: 'Let me nip this in the bud right now – pun intended'
Ariana Grande nude photos leak: Pictures are completely fake, say representatives
Saudis risk new Muslim division with proposal to move Mohamed’s tomb
Kate Upton nude photos leak: Model's spokespeople 'looking into' authenticity of indecent images
Rotherham child sex abuse scandal: Labour Home Office to be probed over what Tony Blair's government knew - and when
What do immigrants really think of Britain? Polish immigrant's Reddit post goes viral
Ashya King: Parents of five-year-old boy refused permission to visit him in hospital and denied bail at Spanish court
With Douglas Carswell joining Ukip, my party has taken another giant step forward
When elitism grips the top of British society to this extent, there is only one answer: abolish private schools
Ashya King: 'Cruel NHS has not given us the treatment we need', says father of five-year-old with brain tumour who fled to Spain
£500 per day: Harrington Starr: C#.NET Developer C#, WPF, WCF, ASP.NET, Prism...
£8 per hour: Randstad Education Leeds: The Job Creche Assistant to start asap ...
£8 per hour: Randstad Education Leeds: The Job Nursery Nurse Leeds We are now ...
£55000 - £65000 per annum: Harrington Starr: A Global Financial Service Organi...