The Jet Stream is a Complex River of Air!

I remember writing a paper about the Jet Stream in college. It was well before personal computers, so most of my research was based on published papers found in the library, the paper was hand typed, one copy was submitted and it was never to be seen again.  Ahh the good old days. Not really, there is such a wealth of knowledge on the web now we can all pretend to be experts.  What I did learn, is that the Jet Stream is extremely complex.  This string of pearls drags weather along with it, it reaches speeds in excess of 300 kph. Planes have avoided or used these winds to go faster for decades!

Polar and Sub-tropical Jet Streams Control our Weather

A Tunnel of Wind

Most people never really understand the impact that the Jet Stream has on our day to day weather.  I know that years ago Television Weather People (not Meteorologists) rarely talked about it.  They would mention low or high pressure systems (cyclones and anti-cyclones), but the jet stream was a bit more complicated for them or the general public to fathom.  The mention of the jet streams impact on our weather is much more popular today as television meteorologists are much better educated and the public more savvy.

NASAs Image of an amplified Jet Stream

Basic Meteorology Explained

There is a lot more involved to it than just knowing the definitions of weather phenomena.  Other events that may impact our weather include phases of the moon (like the full moon that occurred during Hurricane Sandy!),  the conveyor belt of ocean currents (thermohaline circulation), the melting of the Arctic ice cap, Coronal Mass Ejections (Solar Flares),  and of course the oft mentioned green house gases that warm the earths surface.

So fortunately or unfortunately all of these forces are occurring at the same time on our earth and if one element becomes stronger or weaker we usually suffer the consequences in some unexpected event.  A disruption in the force you might say (for all the Star Wars aficionados out there!).

If you want to try to understand the basic principles of our ocean of air, I recommend you check out the links below;

http://geography.about.com/od/climate/a/jetstream.htm

http://en.wikipedia.org/wiki/Jet_stream

http://en.wikipedia.org/wiki/Cyclone

http://en.wikipedia.org/wiki/Anticyclone

http://en.wikipedia.org/wiki/Thermohaline_circulation

http://earthobservatory.nasa.gov/Features/ArcticIce/

http://www.crh.noaa.gov/fsd/?n=sunspots

http://www.epa.gov/climatechange/ghgemissions/

Low Pressure System

High Pressure System

Both Low and High Pressure Systems travel along with the Jet Stream

Climate Central talks a lot about CC and the JS!

Climate Central uses the UN IPCC study to give the most definitive reasoning why climate change is impacting the Jet Stream and what potential impacts it might have on our weather!

“The latest U.N. IPCC climate report, which states: “It is likely that circulation features have moved poleward since the 1970s, involving a widening of the tropical belt, a poleward shift of storm tracks and jet streams, and a contraction of the northern polar vortex. Evidence is more robust for the Northern Hemisphere.” The research that goes into this statement comes from multiple lines of evidence – from analyses of the expansion of the tropical Hadley Cell to satellite measured outgoing radiation, radiosonde observations, and weather pattern reanalyses…”

What I read is “widening of the tropical belt”…doe’s this mean larger stronger hurricanes, tornadoes and typhoons?

“poleward shift of storm tracks and jet streams…” doe’s this mean more drought to the mid-west and more erratic stronger cold or heat events?

“contraction of the northern polar vortex…” doe’s this mean the jet stream brings warmer air to the Arctic?

They go on to say…” The work of Dr. Jennifer Francis and Steven Vavrus shows that as the Arctic warms faster than the tropics, a lessening of the temperature gradient between the equator and the North Pole slows the jet stream. As the jet stream slows, it supports a “wavier,” more frequently amplifying jet that increases the probability of extreme weather events, known as Arctic amplification.”

The argument in these initial paragraphs are strong evidence that there is a correlation between climate change and the jet streams effects on extreme weather events.  They do point out other researchers who believe they could not find any “clear trends” and those who “found no significant increase in the frequency of blocking events over North America and the North Atlantic, indicating that severe mid-latitude storms cannot simply be understood through Arctic amplification alone”.

“This research does not mean that Francis and Vavrus’ hypothesis is wrong, it simply means that the atmosphere is complex and more research is needed.”

Sounds to me like typical scientific “more research is needed” reasoning. Yet they are correct…The weather on our planet is indeed complex and while we have some strong examples of change since record keeping began…there are so many factors at play that we really just don’t know for sure!

Read for yourself at the following link;

http://www.climatecentral.org/gallery/graphics/climate-change-the-jet-stream

And What about a Polar Vortex?

Don’t Go Outside Without a Warm Coat!

The deep freeze Polar Vortex that the Mid-West and Eastern States suffered this past month is an example of the “Extreme meandering of the Jet Stream”.  Has this happened before?  Of Course!…However will it become more frequent in the future should be the question.  Meteorologists will wait for several decades before they place too much correlation between the two phenomenas!

Wiki does link the two however and it’s only common sense to think that the potential for more extreme events lies waiting in the wings!

“The general assumption is that reduced snow cover and sea ice reflect less sunlight and therefore evaporation and transpiration increases, which in turn alters the pressure and temperature gradient of the polar vortex, causing it to weaken or collapse. This becomes apparent when the jet stream amplitude increases (meanders) over the northern hemisphere, causing Rossby waves to propagate farther to the south or north, which in turn transports warmer air to the north pole and polar air into lower latitudes. The jet stream amplitude increases with a weaker polar vortex, hence increases the chance for weather systems to become blocked. A recent blocking event emerged when a high-pressure over Greenland steered Hurricane Sandy into the northern Mid-Atlantic states.^[24]”

http://en.wikipedia.org/wiki/Polar_vortex

“Should we be worried?”

That is the basic question!

To worry is not necessary.  To understand about the factors that may affect our lives and our families lives in the future is however.  Basic Meteorology seems simple enough but it is really complex.  There are so many elements at play out there most people don’t understand what impacts it might have on them.  Scientists are concerned and there are many new studies out there trying to understand whats going on.  Let’s wish them well.  Until then, be prepared for the cold or the heat, or the winds, or the drought, or the floods that may impact your lives.