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What is the polar vortex?

The polar vortex circulates cold Arctic air in the jet stream.

The “polar vortex” has been in the forecast lately as winter ramps up, making for a cold start to the spring semester, but what exactly is a polar vortex?

NCC’s Weather and Climate Professor Anita Forrester to helped explain.

The polar vortex is a pocket of cold air that swirls around the arctic poles moving along the jet stream. In the winter the size of the vortex expands which sends cold air in our direction.

But as warm air enters the jet stream it weakens the speed of the vortex, which in turn slows it down and causes it to “wobble’ and eventually split. The split causes the cold air to shift southward.

“Imagine riding a bicycle,” Forrester explained. As you gain speed, you are able to maintain balance and stability. Centrifugal force keeps you on a stable course as you move in a circular rotation. Now imagine slowing down. Trying to retain balance becomes difficult and you begin to wobble. This is similar to what it is like in the jet stream.

The polar vortex is a completely normal. What is unusual is the warming temperatures in the Arctic.

In recent years, the Arctic region has experienced temperatures above freezing, causing ice melt. According to NASA’s Goddard Institute for Space Studies, the Arctic has been warming at an alarming rate for the past 40 years.

“As the Arctic experiences heatwaves, we are experiencing colder temperatures,” Professor Anita Forrester said.

If the predictions for February are correct, we will not see many days above freezing until late in the month. Along with the cold, there will be snow and ice in the forecast.

Students can sign up to receive school closure alerts via text message or email. You can also check the weather information page on the school website northampton.edu, Facebook, or Twitter. An NCC 24-hour weather hotline is also available with information on closures.  Bethlehem Campus and Southside Center: 610.861.4595 or Monroe Campus: 570.369.1800 X 3