Explained: Earth's Polar Vortex Spins Backwards, Scientists Taken Aback

Scientists were taken aback, earlier this month, when they noticed that the Arctic's polar vortex has changed its course and has started spinning in the opposite direction.

This unexpected shift happened around March 4 and ranks among the six strongest occurrences of its kind since 1979, according to Amy Butler, a climate scientist at the National Oceanic and Atmospheric Administration (NOAA), reported Spaceweather.

What is the polar vortex?

The stratospheric polar vortex is a huge spinning wheel of freezing cold air that forms high up in the atmosphere near the North Pole, according to NASA. It is held together by a strong wind current that goes from west to east, circling around the polar region. It is the strongest during winter and helps keep the coldest air trapped around the poles. 

The winds in the polar vortex can reach speeds of about 155 miles per hour, as reported by the UK Met Office, which is almost as fast as the minimum wind speed for a Category 5 hurricane. This wind current is often called the polar night jet. The polar vortex starts from where the stratosphere meets the troposphere and goes up into the mesosphere. 

Why is it spinning backwards?

According to Amy Butler, something called "Sudden Stratospheric Warming events" caused more ozone from lower latitudes around the Arctic to move in which led to the polar vortex changing direction unexpectedly. "Atmospheric planetary waves have been breaking in the polar stratosphere, increasing its temperature," Ms Butler told SpaceWeather. 

The reported "ozone spike" is the largest in March since 1979. 

What effect will it have?

The polar vortex is known for causing extreme cold and storms in different regions. However, in this case, no such extreme weather has occurred according to Ms Butler, who wrote NOAA's new polar vortex blog.