|Fig. 1 Polar Vortex Fragmentation|
Like the ghost water issue, I have written about this ongoing Polar Vortex disintegration we are now watching and feeling (Watching The Arctic Die, 2).
The reality is that the Arctic Polar Vortex continues to suffer pieces breaking off into smaller pieces in winter time (in fact I was watching the Weather Channel a few minutes ago while they were talking about "two pieces" of the vortex causing extreme cold in the U.S.A. even as we blog ... "when this warm air flows north like this it splits the polar vortex into several pieces in some cases" - Dr. Gregg Postel).
|Fig. 2 Arctic Ice Conditions 29 Dec 17|
This record low sea ice extent in the Arctic is taking place as we here in "the states" are and have been seeing record cold in some places.
Even the President, a climate change denier, noticed and mentioned that it would be ok to have some "global warming" to ease the coldness.
These very cold pieces of the Arctic Polar Vortex separate or break off then flow south until they meld and blend into the warmer air until equilibrium takes place (e.g. Second Law of Thermodynamics).
I have mentioned this here on Dredd Blog for several years, in various contexts:
The strife caused by the extreme weather is being blamed on a “polar vortex", a spinning wind that in normal years has a beneficial effect in that it keeps sub-zero air trapped above the North Pole. A weakened polar vortex has allowed the trapped air to spill out of the Arctic and hurtle south in an anti-clockwise movement across the face of the US.(The Damaged Global Climate System , On The Origin of Tornadoes - 5, On The Origin of Tornadoes - 6). Record low sea ice extent and record cold areas in the U.S. are symptoms of damage to the global climate system by global warming.
Just why the polar vortex has proved to be too weak to contain the cold air this winter will be a matter for intense scientific study and debate for some time to come. The phenomenon might in large part be explained by the natural changes in climate that occur in the Arctic in winter, including the North Atlantic Oscillation that has a dominant impact on wind patterns and storm tracks in the region.
But Noaa, a federal agency, has also floated the possibility that a reduction in summer sea ice cover caused by climate change could be a factor behind the weakening of the polar vortex. That would have the paradoxical effect that while Arctic waters are getting warmer, North America experiences much colder snaps such as the present severe weather as a result of Arctic air spilling out from the North Pole and moving south.
A mechanism to explain how the behavior of the stratosphere may affect tropospheric weather patterns has been proposed by scientists at the
University of Illinois. If correct, the idea could be included in models to better understand the climate system and predict the weather.
Normal polar vortex
“Recent observations have suggested that the strength of the stratospheric polar vortex influences circulation in the troposphere,” said Walter Robinson, a UI professor of atmospheric sciences. “We believe there is a weak forcing in the stratosphere, directed downward, that is pinging the lower atmosphere, stimulating modes of variability that are already there.”
The polar vortex is a wintertime feature of the stratosphere. Consisting of winds spinning counterclockwise above the pole, the vortex varies
in strength on long time scales because of interactions with planetary waves global-scale disturbances that rise from the troposphere. “The polar vortex acts like a big flywheel,” Robinson said. “When it weakens, it tends to stay weakened for a while.”
At (d) a piece breaks away
Other researchers have noted a statistical correlation between periods when the polar vortex is weak and outbreaks of severe cold in many Northern Hemisphere cities.
“When the vortex is strong, the westerlies descend all the way to Earth's surface,” Robinson said. “This carries more air warmed by the ocean onto the land. When the vortex is weak, that's when the really deep cold occurs."
Under normal climate conditions, cold air is confined to the Arctic by the polar vortex winds, which circle counter-clockwise around the North Pole. As sea ice coverage decreases, the Arctic warms, high pressure builds, and the polar vortex weakens, sending cold air spilling southward into the mid-latitudes, bringing record cold and fierce snowstorms. At the same time, warm air will flow into the Arctic to replace the cold air spilling south, which drives more sea ice loss.
The next post in this series is here, the previous post in this series is here.
Ode to Pruitt, Trump & Inhoff, Inc.