Powerful polar vortex in the stratosphere brings frigid temperatures to US
A blast of arctic air from Canada has brought the season's coldest weather to most of the United States. The system, known as a polar vortex, is forecast to bring subzero temperatures to the Midwest, Mid-Atlantic and deep into the South.
And it looks as if we may get more arctic blasts in the coming years.
Outbreaks from the Arctic will persist throughout the Northern Hemisphere in the upcoming decades, even as the region is warming more quickly than the rest of the world, according to a study published in the journal Environmental Research: Climate.
Strong wind gusts are expected from Montana to Nebraska this week, according to Accuweather. The freezing temperatures will move eastward, reaching major cities like Philadelphia, where daytime highs will reach only the upper teens.
How the stratosphere influences Earth's surface climate
The polar vortex is a gigantic circular upper-air weather pattern in the Arctic that envelops the North Pole. It's a normal pattern that is stronger in the winter and tends to keep the coldest weather bottled up near the North Pole.
The jet stream typically acts as a barrier to keep the polar vortex contained near the Arctic, but at times, some of the vortex can break off or move south, bringing unusually cold weather into the U.S., Europe and Asia.
The images below show how the influence of climate change from as far away as the mid-latitudes can trigger an outbreak of arctic air over the United States weeks to months later.
Unable to view our graphics? Click here to see them.
Polar vortex and jet stream are both extending southward into the US
The National Oceanic and Atmospheric Administration's Global Forecasting System model predicted the polar vortex would shift south of the tropospheric jet stream over North America, with the stretched polar vortex corresponding to the shift.
Where is the stratosphere?
Let's examine the atmosphere's structure. The troposphere, which extends up about 6 miles from the Earth's surface, is the first layer of the atmosphere. The majority of our weather occurs here. The layer of the atmosphere that lies between 6 and 31 miles above the surface is known as the stratosphere. The polar vortex is within the stratosphere.
Because of the lack of sunlight, both the Earth's poles have substantially cooler temperatures than the equator. This means the air at the poles gets extremely cold and dense, which causes a powerful jet stream to emerge in the stratosphere and blow the cold air from west to east. This strong circulation is known as a polar vortex.
This story was updated to fix a typo.
CONTRIBUTING Anthony Robledo
SOURCE NOAA, Climate.gov, NASA and Royal Meteorological SocietyThis story was updated to add new information.