How the polar Vortex caused a massive winter storm in the US

Context: The US and Canada were hit with a massive storm over the weekend,
leading to mass school closures, dangerous road conditions, and power cuts. At
least five people died in the storm, which impacted some 60 million dollars of
damage in 30 US states and has sent temperatures plummeting across much of the
continent. The cause of this extreme weather is the southward expansion of the
polar vortex. Scientists are still researching the precise impact of climate
change on the polar vortex, and if rising temperatures are making the
low-pressure system buckle more frequently.

Key points

·       Overview: A deadly
blizzard (snowstorm) has gripped the United States & Canada, leading to
multiple deaths and complete disruption of normal life.

·       Background: Recently, a
study was published in Science.org, revealing that the rapid warming of the
Arctic might be allowing frigid air in the region to move southward more
frequently than ever before. The study largely focused on something called the
polar vortex, which is a mass of cold, low-pressure air that consistently
hovers over the Arctic region.

·       Findings
of the Study: In the study published in the Science.org, the
researchers found that the expansion of the polar vortex has been occurring
more than twice as often in recent years and the reason for it is the rapidly
warming Arctic. With the help of observational analysis and numerical
modelling, the study came to the following conclusion- 

Ø  The melting sea
ice in Barents and Kara seas north of Russia and Scandinavia and increasing
Siberian snowfall create larger and more energetic atmospheric waves.

·       Polar
vortex: It is a large low-pressure and cold air system that surrounds the
Earth’s poles. It always exists near the poles but becomes stronger in winter
and weaker in summer. The term “vortex” refers to the counterclockwise flow of
air, which keeps cold air confined near the poles.

Ø  Tropospheric
Polar Vortex - Found in the lowest atmospheric layer (up to 10-15 km), where most
weather events occur.

Ø  Stratospheric
Polar Vortex - Found at higher altitudes (15-50 km), strongest during autumn and
disappears in summer.

·       Key
Features of the Polar Vortex: Northern Hemisphere Vortex - Has two
main centers, near Baffin Island, Canada. In northeastern Siberia.

Southern
Hemisphere Vortex - Typically located around the South Pole. Stronger
and more stable compared to the northern vortex, making it less likely to
wobble.

·       Working
of Polar vortex: Constant Spin - The vortex spins
counterclockwise around the North Pole throughout the year.

Seasonal Shifts
-
In summer months, the vortex sits at higher latitudes. In winter months, it
shifts southward.

·       Causing
extreme cold: When the polar vortex weakens, cold Arctic air
moves south, bringing freezing temperatures to regions like the US, Europe, and
Asia.

Ø  Role of the Jet
Stream - A strong polar vortex keeps the jet stream stable, trapping cold air in
the north and keeping warm air in the south. When the polar vortex is strong,
the polar jet stream locks bitterly cold, dry air in place over the Arctic.
When strong, these winds essentially act as an unscalable wall that frigid air
cannot breach.

Ø  Impact of
High-Pressure Systems - A strong area of high pressure near the Arctic
disturbs the polar vortex. High-pressure systems can disrupt the jet stream,
pushing the cold air even farther south, leading to extreme cold in unusual
areas.

·       Image
of Global Warming on the Polar Vortex: Global warming impacts the
polar vortex, causing changes in weather patterns and leading to extreme cold
events.

Ø  More Extreme
Cold Spells - Even though global temperatures are rising, warming in the Arctic can
lead to more cold weather in some regions, this happens because warmer
temperatures in arctic makes the vortex unstable allowing cold air to move
south.

Ø  Faster Arctic
Warming - The Arctic is warming faster than the rest of the world, a phenomenon
called Arctic amplification. This makes the polar vortex more likely to cause
cold air outbreaks in lower latitudes.