Rising Arctic temperatures and melting sea ice could be causing cold air to flow into the Northern Hemisphere. But not all scientists agree.

Meteorologists warn that a stretched polar vortex could bring severe winter weather to much of the United States.

The North Pole is surrounded by a massive circular upper-air weather phenomenon in the Arctic called the polar vortex. It is a typical pattern that tends to contain the coldest weather close to the North Pole and is more pronounced in the winter.

Much of the nation east of the Rocky Mountains is hunkered down for what could be the worst winter storm of the season.

Tens of millions of people are in the path of a major winter storm. Federal cuts threaten efforts to understand the causes of such weather.

What is the Polar Vortex? The polar vortex is a large area of low pressure and cold air surrounding the Earth's poles. Normally, this cold air remains contained within the Arctic Circle, but disturbances in the atmospheric pressure can cause it to move southward.

A snowstorm and harsh winter weather have impacted at least 177 million people across the US