Structure
Introduction: (upto 30 words) Start the answer with an introduction about POlar vortex.
Body: (upto 100 words) Explain more about Vortex and its impact on climate
Conclusion: (upto 30 words) Conclude by writing that, the Polar Vortex also causes Ozone hole at the Poles.
Supporting Points:
A polar vortex is an upper level low-pressure area lying near the Earth's pole. There are two polar vortices in the Earth's atmosphere, which overlie the North, and South Poles.
Each polar vortex is a persistent, large-scale, low- pressure zone that rotates counter-clockwise at the North Pole (called a cyclone), and clockwise at the South Pole.
- A polar vortex strengthens in the winter and weakens in the summer due to its dependence on the temperature difference between the equator and the poles.
- The vortices span less than 1,000 kilometres (620 miles) in diameter within which they rotate counter-clockwise in the Northern Hemisphere, and in a clockwise fashion in the Southern Hemisphere. As with other cyclones, their rotation is driven by the Coriolis Effect.
- Normally, when the vortex is strong and healthy, it helps keep a current of air known as the jet stream traveling around the globe in a pretty circular path. This current keeps the cold air up north and the warm air down south.
- However, without that strong low-pressure system, the jet stream doesn’t have much to keep it in line. It becomes wavy and rambling. Put a couple of areas of high-pressure systems in its way, and all of a sudden you have a river of cold air being pushed down south along with the rest of the polar vortex system.
Impact on Global climate:
- In early January, the polar vortex weakened and broke down, allowing fragments of cold air to slosh out of the bowl into mid-latitudes.
- The high pressure building up in the Arctic slowed down the jet stream, which caused it to buckle into deep folds and flow farther south than usual, introducing cold Arctic air into the central and eastern U.S.
- In recent years, climate scientists have noticed that the jet stream has taken on a more wavy shape instead of the more typical oval around the North Pole, leading to outbreaks of colder weather down in the mid-latitudes and milder temperatures in the Arctic, a so-called “warm Arctic-cold continents” pattern.
- However, less sea ice and snow cover in the Arctic and relatively warmer Arctic air temperatures at the end of autumn suggests more wavy jet stream pattern and more variability between the straight and wavy pattern.
The chemistry of the Antarctic polar vortex has created severe ozone depletion. The nitric acid in polar stratospheric clouds reacts with chlorofluorocarbons to form chlorine, which catalyzes the photochemical destruction of ozone.
