All the fifty states of US recorded sub-freezing temperatures in January 2014. Bitter cold created logjam across all the transportation services. The shivering cold also caused power shortage and adversely impacted daily routine. These low temperatures were not experienced in the region, since the last 20 years. Experts explained that Polar Vortex could be the main culprit behind this brutal cold.
About Polar Vortex
• Polar Vortex is a low pressure, upper level (primarily in stratosphere) wind system rotating in anticlockwise direction.
• Wind Velocity of this system is more than 100 miles per hour.
• Generally, this vortex remains confined to the Arctic region. When the Polar Vortex weakens or splits, these cold winds move out of the Arctic and move towards South. The weakening of the Polar Vortex is attributed to the change in the intensity of the upper level winds that build Polar Vortex.
• Polar Vortex can occur anywhere in the Northern hemisphere.
• The vortex is strongest in winter, due to more temperature contrast between the Polar Regions and the mid-latitudes.
• Often, Polar vortex is misunderstood as hurricanes or tornadoes. But, these are different phenomena. The areas covered under the influence of the polar vortex are much wider than hurricanes or tornadoes. Polar Vortex lasts for more days than hurricanes or tornado.
Role of Polar vortex behind low temperatures in US
Recently, Polar Vortex weakened in the arctic region. This weakening forced cold air to move in the areas south to the arctic region. Thus, this wind covered entire North America bringing record low temperatures in this region. However, Polar Vortex is touted as only a possible reason. There could be one or more reasons behind the low temperatures in US.
Whether polar vortex itself is an outcome of global warming or not is still a matter of debate.