BY REBECCA JASULEVICZ
On January 2, 2014, a cold front made its way across the continental United States, breaking low temperature records and resulting in heavy snowfall.
Businesses, schools, and even some airlines were forced to temporarily close due to a weather system known as a polar vortex.
A polar vortex is a semi-permanent weather system that occurs when an area of low pressure in the upper atmosphere exists, most often near the Earth’s poles.
The polar vortex typically resides in the stratosphere, the layer of atmosphere above the troposphere, which is the lowest portion of Earth’s atmosphere where most weather occurs.
In this instance, the polar vortex’s main circulation occurred over northern Greenland and Baffin Island. However, as January began, a portion of the vortex extended itself southward into the United States.
At the same time, other disturbances in the atmosphere were able to merge with the vortex, causing a jet stream to plunge southward as well.
Jet streams are narrow, fast-moving air currents that circulate around the Earth in the troposphere or near the area where the troposphere and the stratosphere meet.
Jet streams are known to have several causes, including the rotation of the planet on its axis and heat from the Sun.
On other planets, jet streams may also receive the heat they require from the planet’s internal heat.
The combination of atmospheric disturbances with the movement of the polar vortex is believed to be what caused the extreme surge of cold throughout the country.
While this is the short-term explanation of this weather, the underlying reason is hypothesized to be global climate change.
Climate change is the overall pattern of the Earth’s weather, including changes in temperature, wind patterns, and rainfall.
The Earth’s temperature has steadily been increasing, especially because of increasing levels of particular gases in the atmosphere, including carbon dioxide, ozone, and methane.
Climate change is caused not only by these gases, usually termed “greenhouse gases,” but also by a myriad of other factors, some of which include radiation from the Sun, the movement of the Earth’s tectonic plates, and volcanic activity.
Recently, human activities have also been added to the list of possible causes of climate change, as many human activities produce large quantities of greenhouse gases and remove vegetation that may aid in removing these compounds from the atmosphere.
“Long-term trends in surface temperatures are unusual and 2013 adds to the evidence for ongoing climate change,” said Gavin Schmidt, a climatologist from the NASA Goddard Institute for Space Studies.
According to the National Oceanic and Atmospheric Administration, there are several indicators that show that global climate change is currently occurring.
These indicators include increases in temperature of the troposphere, land, and oceans, higher humidity levels, and an increase in the current sea level.
In addition, there has been a decrease in glacier size, sea ice, and overall snow cover in elevated altitudes.
Many scientists consider glaciers to be one of the most sensitive indicators.
Glaciers are known to grow and shrink depending on variations in temperature, precipitation, and natural movement, the study of which is known as hydrology.
As the average temperature warms, glaciers retreat unless enough snow is produced to make up for the additional melt.
Prior to January’s cold surge, caused by the polar vortex, several studies were conducted and were able to find a correlation between climate change and more extreme temperature fluctuations.
This may give insight as to how disturbances in the atmosphere managed to interrupt the jet stream’s typical circulation.
Scientists believe that because of the melting of glaciers and polar sea ice, more of the Sun’s rays were absorbed by open oceanic waters, as opposed to being reflected back into the atmosphere.
Because of this absorption, the Earth’s poles were heated. Because jet streams are directed in part by the locations of heated areas, this uncommon heating of the poles may have caused the jet stream to become weaker.
This would cause the direction of the current to become more variable, allowing the colder air that is usually confined to the poles to spread southward along with the sudden southward surge of the polar vortex.
While meteorologists are predicting that this winter will continue to be cold, local temperatures are expected to return to above freezing by the end of the week.
With climate change a continuing issue, this may not be the only cold winter in years to come.
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