Cold weather is in the forecast and talk of the polar vortex is swirling on social media. You may be wondering, how does the polar vortex affect us?

The polar vortex is a very cold low pressure churning around the north and south poles. For it to allow fresh cold air to spill southward into Canada, the U.S. or Europe, it has to weaken or collapse. So, how does this happen?

Polar vortex is not just a trending topic but a real atmospheric phenomenon. For the polar vortex to impact our temperatures here in the U.S., it has to collapse or weaken. There are two ways this can happen.

Oscillations or waves of warm air can occasionally push into the stratosphere - the layer just above the troposphere, one layer above us - disrupting the normally circular flow of the vortex. When this happens, it can split into multiple smaller vortices or be displaced from the pole. This displacement then allows the cold air that was contained to move south.

Sudden Stratospheric Warming event (SSW), characterized by an abrupt temperature surge in the polar stratosphere, is another mechanism that can cause the polar vortex to collapse. In fact, SSWs are more common during El Niño years, but can happen at anytime nonetheless.