(Vatican Radio) Temperatures in the United States continue to hit record lows, as
the cold front which has invested much of North America moves towards the eastern
seaboard – and the reason behind this cold snap is said to be a much talked about
“polar vortex”.
Although not many of us had heard of it before last week, the
arctic polar vortex is a large-scale cyclone system which in fact sits permanently
over the North Pole – something like a year-round hurricane producing what is typically
the coldest air in the northern hemisphere. Just like its antarctic counterpart, it
can measure up to 2000km across, sitting high up in the stratosphere and, when it
is strong, keeping the coldest air over the Pole.
Disruption to the system,
however, has caused polar winds to sweep down across the US, bringing arctic temperatures
to northern states such as Montana and lows unseen in several decades as far south
as Alabama. Experts give varying accounts of the exact nature of this disruption:
some say the vortex has been pushed southward by a pressure system originating in
the eastern Pacific, while others say the vortex has weakened and is effectively “spilling”
cold air over the US. Meteorologists also say there is a correlation between the warmer
temperatures experienced earlier this winter and the sudden outbreak of cold.
16
people have died so far in the current cold snap, in a variety of accidents including
car crashes caused by adverse weather and cases of hypothermia. Approximately 187
million people are expected to have been affected by Tuesday.