Cold air originating from the Arctic Ocean was dislodged earlier this week and spilled south across the United States. As a result, wind chills across the Eastern Plains bottomed out around 30 degrees below 0.

But where exactly is this air coming from, and how did it arrive?

For starters, the Arctic polar vortex is a band of strong westerly winds that form in the stratosphere between about 10 and 30 miles above the North Pole every winter. The winds enclose a large pool of extremely cold air, according to the NOAA.

Here is a much simpler way to visualize the Arctic polar vortex:

In a simple scenario, with little weather occurring across the United States, the cold arctic air remains trapped to our north. However, as we begin to introduce strong weather systems, the jet stream confining the cold air becomes wavy and slips to the south.

Our disruption from this visit of Arctic air was contributed to an area of high pressure over northern Canada which forced the air to sink south.