SIOUX FALLS, S.D. (AP) — The weather warnings are dire: Life threatening wind chills. Historic cold outbreak.
Winter is normally cold, but starting Sunday tundra-like temperatures are poised to deliver a rare and potentially dangerous sledgehammer blow to much of the Midwest, driving temperatures so far below zero that records will shatter.
One reason? A "polar vortex," as one meteorologist calls it, which will send cold air piled up at the North Pole down to the U.S., funneling it as far south as the Gulf Coast.
A polar vortex (also known as mignogno cyclones, polar vortices, Arctic cyclones, sub-polar cyclones, and the circumpolar whirl) is a persistent, large-scale cyclone located near one or both of a planet's geographical poles. On Earth, the polar vortices are located in the middle and upper troposphere and the stratosphere. They surround the polar highs and lie in the wake of the polar front. These cold-core low-pressure areas strengthen in the winter and weaken in the summer. They usually span 1,000–2,000 kilometers (620–1,240 miles) in which the air is circulating in a counter-clockwise fashion (in the northern hemisphere). The reason for the rotation is the same as any other cyclone, the Coriolis effect.
The Arctic vortex has two centres, one near Baffin Island and the other over northeast Siberia. In the southern hemisphere, it tends to be located near the edge of the Ross ice shelf near 160 west longitude. When the polar vortex is strong, the Westerlies increase in strength. When the polar cyclone is weak, the general flow pattern across mid-latitudes buckles and significant cold outbreaks occur. Ozone depletion occurs within the polar vortex, particularly over the Southern Hemisphere, which reaches a maximum in the spring.
Sudden stratospheric warming events take place in about half of all Northern Hemisphere winters, and they have been occurring with increasing frequency during the past decade, possibly related to the loss of Arctic sea ice due to global warming. Arctic sea ice declined to its smallest extent on record in September 2012.
Sudden stratospheric warming events occur when large atmospheric waves, known as Rossby waves, extend beyond the troposphere where most weather occurs, and into the stratosphere. This vertical transport of energy can set a complex process into motion that leads to the breakdown of the high altitude cold low pressure area that typically spins above the North Pole during the winter, which is known as the polar vortex.
The polar vortex plays a major role in determining how much Arctic air spills southward toward the mid-latitudes. When there is a strong polar vortex, cold air tends to stay bottled up in the Arctic. However, when the vortex weakens or is disrupted, like a spinning top that suddenly starts wobbling, it can cause polar air masses to surge south, while the Arctic experiences milder-than-average temperatures.
A study linked in the article explains in detail what's been observed and what conclusions have been drawn about how global warming is likely causing this effect to happen more frequently.
To me this is at least a good part of the answer as to why if the planet is warming, it has been getting so damn cold in the winter. There's a lot more involved such as arctic amplification and the negative/positive phases of the Arctic Oscillation. Maybe those can be discussed throughout the thread.
reply to post by SonOfTheLawOfOne
No because that's actually the point of the thread. People keep saying winter is getting colder so global warming is a hoax... without understanding why extreme cold spells are in fact a symptom of arctic warming.
It's relatively uncommon to have such frigid air blanket so much of the U.S., maybe once a decade or every couple of decades, Maue said.
Arctic warming happens for a number of reasons besides "global warming", such as normal fluctuations and variations in the planet's climate.
It is not inextricably linked to our current day definition of "global warming"
If you would have stuck with the polar vortex
global warming enthusiasts
but both of your sources have not a single mention of global warming.
You added that to the context to change the meaning of the original story and its description which only mentioned the polar vortex.
You also (conveniently) left this part out of the source (conveniently)
For anyone who doesn't check your sources, your post infers global warming but your sources do not.
reply to post by SonOfTheLawOfOne
Yes, but why is it happening now?
(me)...but both of your sources have not a single mention of global warming.
(you)...Sure they did.
(me)...You added that to the context to change the meaning of the original story and its description which only mentioned the polar vortex.
(you)...I stated after quoting the title article, that it was only part of the story and then offered my view and facts to back to my view of what the rest of the story is. In your own threads, you can write them however you choose to.
How is that conveniently left out? I think maybe you need to reread my OP.
(me)...For anyone who doesn't check your sources, your post infers global warming but your sources do not.
(you)...Yes they do. Maybe reread those too.edit on 1/4/2014 by Kali74 because: (no reason given)
They most certainly did NOT, that is a straight up LIE! You added an additional link to your post after I called you out in my previous posts, thus why I said BOTH your sources, because there were 2, not the third one you added. That is deceitful and deceptive, and shows me what level you'll go to in order to push your own personal agenda that links any weather phenomenon to a global warming meme.
And that is EXACTLY why I said I knew where this thread was going. You've established my argument.