As polar vortex freezes the North American continent to record low temperatures, a question arises: What is polar vortex?
Photograph: NDTV.com
Polar vortex is also known as polar cyclone, polar low or a circumpolar whirl is a circulation of strong, upper-level winds that normally surrounds the north pole. However, they can be at both the poles. The air in polar vortex circulates in counter-clockwise direction (in northern hemisphere). These winds tend to keep the bitter cold air locked in the Arctic regions of the Northern Hemisphere. Polar vortex generally span less than 1,000 kilometers but occasionally, they can go beyond that. Polar vortices can persist for more than a month.
The upper-level winds change in intensity from time to time. When these winds decreases significantly, the vortex can distort which in turn brings the cold and dense Arctic winds into the southern latitudes. Polar vortex is not a single storm. This decreases the temperature significantly. However, how much cold will happen will depend on the severity of the vortex.
The Arctic vortex in the Northern Hemisphere has two centers, one near Baffin Island and the other over northeast Siberia. In the southern hemisphere, it tends to be located near the edge of the Ross ice shelf near 160 west longitude.
Polar cyclones hover near the poles all year-round. Since polar vortices exist from the stratosphere downward into the mid-troposphere, a variety of heights/pressure levels within the atmosphere can be checked for its existence. Polar vortices are weaker during summer and strongest during the winter.
Some researches believe that global warming can cause polar vortex to come into action. However, there is not much proof to this hypothesis. It has been observed that, Ozone layer depletion occurs when polar vortex reaches its maximum, particularly in the southern hemisphere.
Polar vortex is not entirely the Earth phenomenon as it occurs on different planets and other heavenly bodies as well. It has been observed that polar vortices exists on Venus, Mars, Jupiter, Saturn and even Saturn’s moon Titan.
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