What is Arctic’s Polar Vortex?
In the recent event, the Arctic’s polar vortex is splitting into two and is moving southward. The Meteorologists predicts that the splitting of the polar vortex will result into chilling deep freeze in the US and European countries. This notorious swirl of ultracold winds has been caused around a low-pressure area because of the major stratospheric temperature spike. This will result into sweep across these countries resulting into an extreme dip in temperatures. Weather forecasts suggest that the Canada, Eurasia, Western Europe and the US will undergo the spine-chilling cold winter with heavy snow along the US East Coast.
The polar vortex event is losing stability and it is splitting. The spilling of the vortex causes dramatic, extreme weather implications in the western nations like US and Europe. This ‘disrupted’ polar vortex in the year 2021 will cause the colder air to spill out of the Arctic resulting in the onset of extremely harsh winters.
Polar Vortex is a persistent, large-scale, upper-level low-pressure area. Its diameter is less than 1,000 kilometers (620 miles). This rotates counter-clockwise at the North Pole while in the clockwise at the South Pole. Thus, the polar vortices rotate eastward around the poles. Both the vortices weaken and strengthen from year to year. The rotation of the vortex is driven by the Coriolis effect. Polar vortices are weakest during the summer and strongest during the winter.
Polar vortex was first described in the year 1853. The sudden stratospheric warming (SSW) of the phenomena develops during the winter in the Northern Hemisphere and it was discovered in the year 1952. It was discovered with the radiosonde observations at altitudes higher than 20 km. The phenomenon highlighted in the cold North American winter during 2013–2014. It popularized the term as an explanation of very cold temperatures.
The phenomena of ozone depletion occur within the polar vortices. It happens particularly over the Southern Hemisphere. The ozone depletion reaches to its maximum in the spring.
Arctic vortex of the Northern hemisphere
It is the reoccurring winter phenomenon in which the strong cold winds circle westward around the pole and cause a dark frosty winter. When the vortex of the Arctic is strong, there is a single vortex with a jet stream which is “well constrained” near the polar front. However, when the northern vortex weakens it breaks into two or more smaller vortices. The strongest vortex moves near the Baffin Island, Canada, and while the weakest vortex move near the northeast Siberia. When it is very weak the flow of the Arctic air becomes disorganized. Masses of cold Arctic air push to equatorward that brings a rapid and sharp drop in temperature.
Case Study: Deep freeze in the United States and Canada in late January 2019. It has led to the death of around 20 people due to severe frostbite.
Antarctic vortex of the Southern Hemisphere
It is a single low-pressure zone which is found near the edge of the Ross ice shelf. When the vortex is strong, the mid-latitude Westerlies increase in strength and are persistent. When the vortex is weak, high-pressure zones of the mid-latitudes push poleward, it moves the vortex, jet stream, and polar front equatorward. This brings cold dry air into contact with the warm and moist air of the mid-latitudes. This results in a rapid change of weather which is called as “cold snap”.