Polar Vortex - When Arctic Air Moves South
The polar vortex is a large mass of very cold air that always hovers around the North Pole. It is called vortex because it moves counterclockwise. This area of low pressure lies about 20,000 meters above the surface of the earth.
The polar vortex keeps cold air moving in a tight pattern around the poles. It is usually stronger during the wintertime and weaker in summer. However, sometimes it becomes unstable and breaks out to the south. Because a continent like North America lacks high east-west oriented mountain ranges, the polar vortex can move far south into the continental US . This happens mostly when Greenland and Alaska experience higher than normal temperatures.
When such polar air masses travel southwards, many parts of the American Midwest witness not only temperatures far below zero but also snowfall and heavy winds.
The polar vortex is nothing new, but climatologists suggest that it has been leaving its normal patterns more often in recent years, possibly connected to global climate change.
- Weather and Climate
- Global Warming
- Global Warming Shrinks Polar Bears
- The Differences Between North and South Poles
- Iceberg Traps Arctic Penguins
- The Northwest Passage – Sea Route Through the Canadian Arctic
- climatologist = person who studies the weather and the climate zones of the earth
- continental US = all the states except Hawaii and Alaska
- counterclockwise = in the opposite direction of the way hands of a clock move
- experience = have
- global climate change = temperatures are steadily rising because of more CO2 emissions in the atmosphere
- hover = to stay in one place in the air
- lack = does not have
- low pressure = condition in the atmosphere that affects the weather; low pressure areas lead to the rise of air and rainfall
- pattern = here: the regular way something moves
- suggest = here: to say that something is true
- surface = top part of the earth
- tight = very close
- unstable = to suddenly change its path
- vortex= a mass of wind or water that spins quickly and pulls things to its center
- witness = experience, have