POLAR VORTEX BRINGS COLD SNAP TO US STATES
- The United States is shivering in a deadly cold snap known as a polar vortex. At least eight people have been killed in several states as a result of the Arctic weather.
- The extreme cold has been caused by a blast of Arctic air, which in turn is a result of what is known as a “polar vortex” event.
- States of emergency have been declared in the Midwestern states of Wisconsin, Michigan and Illinois, and even in the normally warmer deep south states of Alabama and Mississippi.
- It is described as a whirling cone of low pressure over the poles that is strongest in the winter months due to the increased temperature contrast between the polar regions and the mid-latitudes, such as the US and Europe.
- The counter-clockwise flow of air helps keep the colder air near the poles. It spins in the stratosphere, a layer of the atmosphere 10-48 km above the ground and above the troposphere, where most familiar weather patterns develop.
- Usually, when the vortex is strongest, cold air is less-likely to plunge deep into North America or Europe. In other words, it forms a wall that protects the mid-latitudes from cold Arctic air.