POLAR VORTEX - GEOGRAPHY
News: Chilly
weather in Asia is due to the same phenomenon that brought extreme cold to the
US last month
What's in the news?
● Scientists
say Asia's extreme cold is largely the
result of the so-called 'polar vortex', the same weather phenomenon that
brought exceptionally cold weather to the United States last month.
Polar Vortex:
● The
polar vortex is a large area of low
pressure and cold air surrounding both of the Earth’s poles.
● The
system has a whirling mass of cold air
circulating in the mid to upper-levels of the atmosphere, flowing
counter-clockwise.
● This
flow of air helps in containing the colder air within the poles.
What is a "polar vortex" event?
● Normally,
when the vortex is strong and healthy, it helps keep a current of air (the jet
stream) travelling around the globe in almost a circular path.
● This
current contains the cold air north of it and the warm air south of it.
● But
in winter, in the northern hemisphere, the polar vortex sometimes becomes less
stable and expands.
● This
occurs when there is a lack of a strong
low-pressure system, resulting in jet stream losing the hold to keep it in
line, and becoming wavy.
● So
a wave of cold air will be pushed down south.
● This
is called a polar vortex event, defining the “breaking off” of a part of the
vortex.