Polar Vortex and Its effects

Polar Vortex and Its effects

What is the News?

• A record-breaking cold wave has swept through the US Midwest, with 22 states hitting sub-zero temperatures. Among cities, Chicago dropped to a low of -30°C, slightly above the city’s lowest-ever reading of -32°C from January 1985.
• 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.

What is a Polar Vortex?

• A polar vortex is an upper-level low-pressure area lying near one of the Earth’s poles.
• There are two polar vortices in the Earth’s atmosphere, overlying the North and South Poles.
• During winter, the polar vortex at the North Pole expands, sending cold air southward.
• 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.
• It ALWAYS exists near the poles, but weakens in summer and strengthens in winter.
• The term “vortex” refers to the counter-clockwise flow of air that helps keep the colder air near the Poles.
• Usually, when the vortex is strongest, cold air is less-likely to plunge deep into North America or Europe.

Effects of Polar Vortex

• When the polar vortex is strong, temperatures are mild in the mid-latitudes across the Eastern US and Northern Eurasia and this creates strong low pressure in the Arctic region.
• During strong polar vortex, the air flow is fast and in a direction from west to east.
• When the polar vortex is weak or “perturbed”, the flow of air is weaker and meanders north and south (rather than west to east).
• During a weak polar vortex, high pressure occurs in the Arctic region and temperatures tend to be cold across the Eastern US and northern Europe and Asia.