What is a Polar Vortex? Explain the Duration and Strength of Polar low-pressure. How Polar Vortex and Global Warming related? What are the Impacts of Polar low-pressure on Earth’s atmosphere? How are Polar Vortex and Ozone layer Depletion related? Read more.
Polar vortices have been in the news ever since the northern hemisphere saw its coldest period during the winter of 2013 – 2014.
The same cold spell had come once again in 2020 when the United States of America, Canada, and Russia experienced one of the coldest winters on record.
What is a Polar Vortex?
A polar vortex or polar low-pressure area is a vast region with low-strain and freezing air covering both the planet’s poles. The literal meaning of the term vortex is the anti-clockwise movement of air that retains the cold air nearby the poles.
It is observed that throughout the winters in Northern Hemisphere, the polar low-pressure becomes comparatively less stable and often expands, sending cold Arctic air toward the south over the US with the jet stream.
It is primarily present in the upper troposphere that sometimes extends to the lower stratosphere, especially at the poles. It is a constant low-pressure area that rotates at the upper level of the north pole in an anti-clockwise direction, and at the South Pole, it rotates in a clockwise direction.
The polar low-pressure area has been in the bulletins afterwards the northern hemisphere faced its coldest age or phase during the winter season of 2013-2014. Furthermore, this same freezing air force came back in 2020. This time countries like the USA, Canada, and Russia suffered undergone one of their coldest winter seasons ever recorded.
Duration and Strength of a Polar Vortex
The duration and strength of a Polar Vortex are as follows:
- A Polar low-pressure area is at its highest during the winter and its lowest during the summer.
- In the event of a volcanic eruption, a polar vortex will be further strengthened and it can stay that way for up to two years after the initial eruption
- There will be a single vortex when the Arctic low-pressure is elongated in shape with two cyclone centres.
- The Antarctic polar low-pressure is far more persistent than the Arctic variant.
- Climate phenomena related to the La Nina will significantly strengthen a polar low-pressure.
- The Arctic polar vortex breaks up between mid-March to mid-May. This event marks the end of winter and the beginning of spring. Farming activities, ecosystems, and other weather cycles are impacted by this event
- The same transition also impacts sea ice, ozone, air temperature, and cloud formation as well.
- An early breakup of the polar low-pressure leads to one warming period that lasts from late February to mid-March. A late breakup period will lead to two warming periods, one in January and one in March.
- There are times when the polar vortex breaks off before the end of the last warming period. If it is big enough then it can move into Canada and the Midwestern, Central and Northeastern United States
Polar Vortex and Global Warming
Many a time, the polar low pressure is associated with global warming. It is believed that many global warming issues are caused due to polar Vortex.
- The worldwide temperature has increased by approx. 0.8°C since the 1880s.
- The Arctic has heated and melted at more than double the rate due to the polar low pressure.
- The North Pole, North America, and other similar regions have very little temperature difference from the Arctic region.
- The jet stream’s energy moves upward, disturbing the Polar Vortex and initiating it to split.
Impacts of Polar low-pressure area on Earth’s atmosphere
A polar vortex and its related events can have the following impacts on the Earth’s environment.
- The Polar low-pressure breakups in the higher atmosphere can have significant sudden or delayed impacts on the environment, such as decreasing atmospheric temperature and extremely harsh cold in the winter in the Eastern United States, Western regions & Northern Europe.
- Abrupt stratospheric warming due to the polar Vortex can lead to the warm Arctic region in the stratosphere as well as the troposphere.
- The warm Arctic region works in favour of cold air and causes more harsh winter weather in the Northern Hemisphere and mid-latitudes comprising the Eastern United States.
Features of Polar Vortex
A polar low-pressure swirls over the stratosphere, 10-48 Km above the ground level.
- A stronger or more potent polar vortex act as a protective barrier for the mid-latitudes protecting them from cold Arctic air.
- Typically, it happens when the polar low-pressure is most potent and cold air is less prone to fall deep into the mid-latitudes, including Northern US and Europe.
- However, the polar Vortex sometimes gets disrupted or weakens because of the wave energy rising skyward from the Earth’s lower atmosphere.
- Such happenings or events with the polar Vortex abruptly warm the stratosphere in just a few days, and this event is known as sudden stratospheric warming far above the Earth’s surface.
- As a consequence of this stratospheric warming, the polar low-pressure tends to shift its location a little toward the south of the north pole. Sometimes this shift splits the polar Vortex into ‘sister vortices’.
Slipping or Shifting of the Polar low-pressure area
A Polar vortex goes across somewhere above 650 North and South latitudes.
- The polar Vortex becomes very powerful when the temperature contrast between the polar low-pressure and temperate regions is highest. At this stage, its meandering is insignificant or nearly null.
- However, the polar vortex meander is known as Rossby waves when this temperature contrast is slight.
- The slight temperature contrast does not mean the summertime.
- The meandering polar Vortex generates irregular or flashing low-pressure & high-pressure chambers.
- High-pressure chambers are formed underneath the ridges, and low-pressure chambers are formed underneath the troughs.
- It happens because of the upper air circulations shaped by the polar low pressure.
- Due to the severe meandering of the Polar low-pressure, the high-pressure chambers force over to the north and shift the polar low-pressure from its standard position.
- It means the polar low-pressure moves far from the pole and glides into the temperate regions having extremely low pressure.
- As soon as the polar low-pressure holds back its strength, the high-pressure chambers become ineffectual and move back to their original latitudinal positions.
- The polar vortex shifts or slips back to its original position or poles with the shift in high-pressure chambers.
How polar vortex shifts to the south?
A high-pressure system from the west pushed the jet stream, and a portion of the polar Vortex shifted farther south than the normal position.
That brought a portion of the Polar Vortex well into North America and caused the temperature in the Midwest and the eastern US to dive to zero.
Polar low-pressure area and Ozone layer Depletion
Even though polar low-pressure and ozone layer depletion is two entirely diverse topics, however related phenomena of the Earth’s atmosphere.
There is a constant decline in the total amount of the ozone layer, approx.—4% in the Earth’s stratosphere. Additionally, a considerable reduction in the stratospheric ozone layer is observed in the vicinity of the Earth’s polar regions.
The chemical makeup of the Antarctic polar low-pressure has led to severe ozone depletion. The nitric acid in the stratospheric clouds reacts with chlorofluorocarbons to form chlorine which further accelerates the destruction of the ozone layer.
The only threat of the Polar low-pressure to humans is the degree of cold temperatures that could get low when the polar low-pressure area spreads out and send Arctic air toward the south into the regions that are not cold usually.
The mild winters in the northern regions of the hemisphere which are particularly south of the Arctic circle have led to a decrease in energy consumption by the people.
Article written by Aseem Muhammed
Leave a Reply