A recent study seems to show that fast increases in Arctic temperatures are moving the high-altitude air current, which, in turn, may be responsible for the wintry blast that has swept across North America. A swirling mixture of jet streams, polar vortexes and a warmer-than-normal Arctic have conspired to make the most recent winter in North America one for the record books.
The research suggests the Arctic is warming up. The increase in temperature appears to have altered the jet stream and is triggering weather patterns to stagnate over the U.S.
The jet stream that flows over Northern Europe and North America has started to take a longer path as the North Pole warms. A warming Arctic means there is a smaller difference between the average temperature in the frigid, far north latitudes and the warmer, southern latitudes. As the average, or mean, temperatures start to get closer, the jet path moves, wanders more and slows down. The result is cold, icy weather over North America staying longer in one place.
Temperatures in the northern most latitudes have risen roughly three times faster than the rest of the world. As the spread between temperatures shortens, warm weather is pushed further north and cold weather travels further south. US cities like Atlanta have suffered rare snowstorms and record-breaking freezes while places like Alaska have had unusually warm winters recently.
Other Scientists are in Dispute
While some scientists insist that a changing jet stream is caused by climate change, others dispute the idea. Climatologists have told reporters that there is a lack of evidence showing that global warming can alter the jet stream. Climatologist Mat Collins, of Exeter University, said, “…if this is due to climate change, it is outside our knowledge.”
What Are Jet Streams
Jet streams are the “rivers” of fast-moving and narrow air currents that are found in Earth’s atmosphere. Westerly winds form the major part of the jet streams, with winds flowing from the west. With paths that appear to have no clear direction, jet streams can start, stop or split into two or more channels.
The Northern jet stream normally flows over the center of North America, Europe and Asia. The jet stream over those three continents dips and wanders. The Southern Hemisphere has a different experience with jet streams. While air currents over the Antarctic sometimes slip northward, the jet streams in the Southern Hemisphere mostly circle Antarctica year round.
Jet Streams Discovered
In 1883 Krakatoa volcano, in Indonesia, erupted and weather watchers mapped the effects of the volcano’s smoke and ash for several years. Wasaburo Oishi, a Japanese meteorologist detected a jet stream for a point near Mount Fuji. Using weather balloons to measure upper level winds in the atmosphere, his work went unnoticed outside Japan.
American pilot, Wiley Post, is mainly credited for the discovery of jet streams. Post invented a pressurized suit that allowed him to fly about 20,000 feet. While making several transcontinental flights, Post noticed that his ground speed often exceeded his air speed by a wide margin.
German meteorologist Heinrich Seilkopf coined the term Strahlstromung, “jet streaming” in 1939. The first real understanding of jet streams occurred during World War II. Many pilots consistently noted westerly tailwinds above 100 mph in flights from the US to the UK.
Jet streams in the northern hemisphere guide air patterns and currents. The largest weather phenomena impacted by the change in the jet stream has been the polar vortex.
As America digs itself out from record-breaking temperatures and snow falls, TV meteorologists have been busy talking about something called “polar vortex.” While it might sound like something from the latest horror movie, it is not that scary and the world is not coming to an end.
A polar vortex is a swirling air mass that is always present. Although it’s usually found around the North and South Poles, recently it has been forced to drop into territory that it normally doesn’t visit. As the polar vortex plowed deeper into America than usual, it has resulted in record-breaking temperatures in a wide swath.
The Ohio Valley experienced a once-in-20-year event when the temperature dropped, mid-day, to a minus 12 degrees. On January 17 in Orlando, Florida, the temperature was hovering around 34 degrees at night and the following day the temperature climbed to 56 degrees. The average for that date is usually 71 degrees.
As temperatures in the Arctic continue to rise, the jet stream may continue to combine with weather elements like the polar vortex to bring more extremes globally.
By Jerry Nelson