Winter at the railyards near downtown Chicago
Welcome to winter. On the shores of Lake Michigan there is a lighthouse near the southern tip that can be battered and covered by waves in storms. Make the weather cold enough and it looks like this.
earthstory reblogged
Cedar River when the air temp was -11 degrees.
Source: richherrmann
My vote is – don’t call this the polar vortex After last winter, it seems that the term “Polar Vortex” has become the only way many local weather forecasters are able to describe an outbreak of cold air, and I'm hoping this post might help clear that up for you. (one forecaster got it wrong last weekend, one explained it very well last night). This week will see a major cold snap across North America, but it is fundamentally different from the polar vortex migrations we saw last year. The Polar Vortex, or the polar vortices, are isolated areas that form in the Arctic/Antarctic during the winter seasons. They are like storms; the wind swirls around their heart, trapping extremely cold air at their low-pressure centers. During the 2013 winter, a series of high-pressure waves in the atmosphere repeatedly forced one section of the Canadian Polar Vortex to break off, heading south into North America and deep-freezing the eastern half of the continent. This week's cold snap. does have a few things in common with those major events from last year. The eastern half of North America is about to be hit by an unseasonable cold snap, driven by a batch of arctic air of the sort that circles around the polar vortex. However, the polar vortex itself is likely to stay locked over Canada; there’s plenty of cold air in the northern hemisphere during winter even outside of the polar vortices. This is a much more common pattern for winter - when it gets cold, its often driven by air surrounding the polar vortices because that's where the cold air is. Despite the cold not being caused by the polar vortex, the story of this weather system is interesting enough without adopting the phrase used to describe the much rarer events we saw last year. Over the last few days, the remnants of a major Pacific Tropical Storm, Super Typhoon Nuri, migrated north over the Bering Sea off the west coast of Alaska. That storm produced the lowest measured air pressure ever recorded off the Bering Strait – a signal of an incredibly intense storm, comparable in intensity to Hurricane Sandy when it made landfall. The heart of that storm is slowly decaying over the Aleutian Islands as I write this. Like other tropical cyclones, that storm turned counter clockwise, so air to the southeast of the storm is being drawn to the North. That pulse of warm air being drawn to the north is heading for Alaska, and over the next few days will set up a warm, high-pressure system over mainland Alaska. You can simulate this flow with the right hand rule. Take your right hand, point your thumb upward, and curl your fingers; the warm, tropical air is following the same path as your fingers, wrapping up into Alaska. As a consequence of this pattern, the Jet Stream that normally flows south of Alaska is being pushed North above that state, causing it to bend southward over North America in response and carrying with it the cold air that exists in Alaska and Northern Canada during the winter – but not deflecting either of the established polar vortices. In the next few days, cities in Alaska will be more than 10°C above average, while areas as far south as Texas will see early-season freezing temperatures. Because this isn’t the same phenomenon we saw last winter, the weather pattern will actually be even more stable than the polar vortex migrations of the 2013/2014 winter, making this cold snap last longer than those cold blasts and occur in several pulses. In fact, it’s possible that if this weather pattern lasts long enough, one of the actual polar vortices could collapse southward next week, but that’s a difficult-to-predict, long-term possibility. There’s a little bit of debate about what to call this thing; some places are using the polar vortex term just because they’re not sure what to call it, but really, this is a distinct setup from what drove the weather we saw last year and our language ought to express that. -JBB Image credit: Thursday's low temperatures http://graphical.weather.gov/# Accuweather calling it the polar vortex: http://www.accuweather.com/en/weather-news/polar-vortex-42-states/37049255 Others arguing against the polar vortex name: http://m.washingtonpost.com/blogs/capital-weather-gang/wp/2014/11/10/the-battle-over-the-polar-vortex-and-how-it-should-be-settled/ http://blogs.agu.org/wildwildscience/2014/11/08/note-national-media-stop-using-word-polar-vortex/ More details: http://mashable.com/2014/11/10/typhoon-nuri-bering-bomb-storm/ http://www.slate.com/blogs/future_tense/2014/11/10/the_omega_block_your_wintry_companion_for_at_least_the_next_two_weeks.html
Big satellite animation:
http://blogs.discovermagazine.com/imageo/2014/11/10/evolution-superstorm-culprit-polar-vortex-redux/#.VGI1_4f5Rqt
#Volcanosnowman I got my first snowfall of the upcoming winter last week, and this week North America is facing an early-season outbreak of arctic weather. A typhoon in the Pacific Basin is migrating north towards Alaska today and will, over the next few days, knock the jet stream and an arctic airmass south over the bulk of North America. I even made the mistake of moving farther north this year. This therefore seems like the right day for this photo. This photo shows a geologist from the US Geological Survey on the slopes of Mt. St. Helens in Washington from February, 1983, almost 3 years after the large explosive eruption in 1980. The geologist has a friend holding his radio, belt, and I’m pretty sure that’s a can of mildly chilled beer. -JBB Image credit: https://www.flickr.com/photos/usgeologicalsurvey/14218344980/
Extreme weather and the Jet Stream Recent weather has left the continents of North America and Europe very familiar with the topic of this post; waves in the jet stream and extreme weather.
Last winter, these areas endured multiple big atmospheric waves as the jet stream bent strongly north and south. In North America, the impact was to bring Arctic cold temperatures down to low latitudes, creating a winter more extreme than any seen in the last 30 years. In Europe, these same waves brought an unending series of intense storms, causing flooding and damaging coastlines throughout. There is strong scientific evidence that over the last decade weather is getting more extreme. More extreme rainfall events, more extreme heat waves, more extreme drought, and anecdotally it makes sense that these extremes could be associated with curls in the jet stream like you see here. If you head over to our blog you can see a really cool animation of how these bends migrate and move (http://tinyurl.com/kaougth) New research just published by Dr. Screen from the University of Exeter and coauthors makes a much stronger link between these weather extremes and migrations in the jet stream. They analyzed historic data for the jet stream – treating variations in the jet stream like waves that can be analyzed. The more extreme the migrations of the jet stream, the higher the amplitude of the “atmospheric wave”, as they termed it. Then, they took their analyses for how extreme atmospheric waves were and compared it to data on when weather extremes occur. When they lined up these data sets, they found very strong correlations between how many extreme bends there were in the jet stream and incidents of extreme weather. Of the months they highlighted as particularly extreme, over 75% had unusually strong bends in the jet stream. This research fits with what we saw last winter but it is really important for understanding why we are seeing more intense weather events. As the atmosphere figures out ways to dissipate the energy held in by newly-released greenhouse gases, these events are becoming more frequent. Understanding the links between the changing climate, the jet stream, and the increasingly severe weather will help us make better predictions for how damaging weather will be in the future. -JBB Image credit: NASA Full study: http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2271.html
Antarctic Vortex fed by climate change
Much of the United States was rudely introduced to the phrase “polar vortex” this past winter when a series of high-pressure systems forced Arctic airmasses south, providing North America with deeply cold temperatures.
The northern polar vortex is a consequence of the circulation of airmasses and the planet’s rotation. At the South Pole, a similar setup occurs as shown in this frame from the global wind map project. It can be disturbed in places by weather systems, but overall, air circulates around Antarctica, creating a southern polar vortex that occasionally impacts the weather of surrounding continents.
New research led by a group from the British Antarctic Survey and the University of Canberra used a variety of geologic data to analyze how this southern polar vortex has behaved with time, and found, surprisingly, that it has recently strengthened as a consequence of a warming climate.
The scientists assembled multiple data sets that could serve as proxies for wind strength as well as temperature and after analyzing them found that the Antarctic winds began strengthening rapidly starting in the 1940’s, just at the time when many other climate impacts were beginning to become obvious. The strengthening of those winds has continued up to the present, making the winds today the strongest in over 1000 years. The Antarctic winds are generally dry, and times when those winds migrate to the north may well have contributed to the droughts and wildfires in Australia over the past few years.
This wind strengthening has been measured previously but it was thought to be largely due to the the ozone hole above Antarctica driving more intense circulation. However, the Ozone hole could not have contributed to these winds as far back as the scientists found evidence for them in the geologic record, but the changing climate matches the wind strength changes quite well.
Ironically, one major impact of these strengthening winds is increasing sea ice off the Antarctic coastline. Strong winds around the isolated continent cool surface waters and promote the formation of sea ice. Thus, the sea ice increases in recent years around Antarctica could in fact be strongly influenced by the warming atmosphere. Antarctica is partially isolated from much of the rest of the world by ocean currents and this wind circulation, protecting it from the rapid melting observed in the Arctic and allowing these winds to translate directly to sea ice formation, but as we noted yesterday, the ices on the Antarctic continent aren’t protected enough. Antarctica may illustrate the effects of a warming world in different ways than the northern hemisphere for now, but that doesn’t mean it is isolated or not at risk.
-JBB
Image credit: http://earth.nullschool.net/ Original Paper:http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2235.html Read more: http://www.newscientist.com/article/dn25547-antarctic-wind-vortex-is-strongest-for-1000-years.html
My discussion of the polar vortex: https://www.facebook.com/TheEarthStory/posts/626004947460553
Our last post on Antarctica: https://www.facebook.com/TheEarthStory/posts/687342551326792
Windblown ice threads in Lake Michigan Winds blowing up from the south west are carrying strings of shoreline hugging ice and snow from Washington Island near the lake's western shore. The ice grows near land because it cools faster than the water due to its lower specific heat capacity, allowing the ice to form there first. Two islands by the top left remain uncollared by ice rings, as the lake water around it remains too warm (relatively speaking, I wouldn't be rushing in for a swim just yet) for ice to form. The gridwork on the island are snow bound fields, resting until the spring arrives. The stings vary in thickness depending on the length of coast that feeds them. We shared earlier this year a photo of ice balls in a cove on the same lake at http://tinyurl.com/n6kl3kv. Loz Image credit: NASA
Ice balls on Lake Michigan These were deposited on the beach in the Sleeping Bear Dunes National Lakeshore on the northeastern side of the lake during the polar vortex last January. They form when turbulent supercooled water breaks up a slush layer, where the ice gradually accretes into rough spheres until they reach the shore. Loz Image credit: Ken Scott via EPOD
The Earth Story has brought you photos of ice spheres on the shores of Lake Michigan during winter before (link), here's some video of recently formed ones moving in the waves by the shoreline
FROSTQUAKES If the just plain **** cold isn’t bad enough, don’t be surprised if you find yourself rolled out of your bed some frigid night in what felt like an earthquake. Frostquakes may feel like a typical tectonic earthquake – there may be shaking, there may be rattling, books might fall from shelves, there might be things that go boom in the night; most frostquakes occur between midnight and dawn. Frostquakes can reach what feels like a magnitude 4 on the Richter scale, though they are so localized that they fail to show up on seismographs. A bit more technical sounding term for this phenomenon is “Cryoseism” (from the Greek, Kryo for cold, and “seismos” for earthquake). Frostquakes are caused by the freezing of subsurface water. Water turning to ice is a powerful agent of a geologic process (ice fracturing) that can force (http://tinyurl.com/nsctgau) rocks to crack, mountains to split, and exfoliation of solid stone surfaces. When water that is present in shallow soils and sediments or in cracks and fissures in the ground freezes, it gains ~9% in volume when it becomes ice. This expansion can occur abruptly in extremely frigid temperature conditions, even explosively, and cause fracturing in the shallow subsurface. This sets off shockwaves that act the same as seismic shockwaves. During the on-going Polar Vortex, frostquakes have been reported in Canada and Ohio. Cryoseisms are also phenomena that accompany glaciation, but since this cold snap is not expected to last long enough to blanket Ohio with rivers of ice, be thankful that we haven’t got THAT ****ing cold enough yet! Annie R Photo: by Anna Batsi with a bit of editing by me. http://gizmodo.com/it-was-so-cold-in-canada-the-ground-exploded-1496252183 http://www.ohio.com/news/break-news/cold-temperatures-believed-to-have-caused-frost-quakes-in-northeast-ohio-1.457680 http://www.bbc.co.uk/news/blogs-magazine-monitor-25620598 http://blogs.discovermagazine.com/d-brief/2014/01/07/frigid-temperatures-trigger-rare-frost-quakes-in-u-s-and-canada/#.Us0XbZ6Sx8E
Here's another video of a body of water steaming. This time, it's a haunting show of Steam and fog pouring out of Lake Michigan just away from Chicago's Navy Pier.
Seriously, what the ****
Ok, this page is called the Earth Story and we wouldn’t be true to our name if we didn’t post something on the major Earth Story impacting most of our readership…the fact that it’s cold as **** (pick whichever 4 letter word you feel is appropriate) in much of the United States.
The Earth’s climate is driven by one basic fact – the tropics receive more energy from the sun than the poles because the planet is a sphere and the poles angle away from the sun. On a simple planet that did not rotate but had an atmosphere, this setup would cause 2 convection cells to form. Air would rise at the equator, move north and south, cool, and sink at the poles. Countering this flow, cold air from the poles would south towards the equator and be gradually heated until it rises.
This simple circulation pattern is known as a Hadley Cell model for the weather. It is what the Earth tries to do – a conveyor belt bringing excess heat from the equator to the poles where it can be radiated to space.
But Earth rotates. Consequently, air can’t simply head north and south – it gets deflected by the rotation of the Earth and the Coriolis Effect. The single cell pattern is broken up and instead generally forms 3 cells in each hemisphere – one near the equator, a central one, and a cell isolated near the pole, with air rising and sinking at the boundaries between the cells.
At the boundaries between these cells, as a consequence of both the differences in pressure and the Coriolis Effect, the winds are sped up into what we know as Jet Streams.
At the North Pole, the jet stream typically keeps the coldest air somewhat in place. Oh, it migrates north and south sometimes but generally, arctic air swirls to the north, somewhat isolated by that jet stream and the fact that it’s in a different circulating cell.
Except…on occasion, something happening in one cell can push into another cell. If, for example, a high pressure system forms in the center cell, it could push north so far as to knock the other cell out of the way. That’s what you’re seeing in this image and that’s the “polar vortex” you may hear about on the news.
Normally the polar vortex sits pretty happily up at the North Pole. Today, it’s been pushed into the United States. The location of the jet stream was bent to the north, in part driven by high pressure over the Pacific and western U.S. As a consequence, the jet stream was forced deep into the southeastern U.S., bringing the air from the arctic all the way down to the Gulf of Mexico.
Of course, there are obviously people laughing at the idea of climate change every time it gets this cold. The first obvious answer is that still ignores what is happening in the southern hemisphere, such as Australia, which is currently mired in another record-breaking heat wave.
Meanwhile, even in a climate changed world, the Arctic will stay extremely cold. The mean average winter temperature in the Arctic is around -40°C (-40°F). So far, the average global temperature has only increased by 1°C; even if the Arctic winter temperature jumped by 10°C it would still be incredibly cold up there. But the science is actually more interesting than just that.
The jet streams are held roughly in place by the temperature differences between the cells – that’s why even in summer it stays pretty cold at the poles, warmer air just doesn't get up there. But, as we've seen over the past few years, the Arctic is one of the fastest-warming places on Earth, with the icecaps shrinking rapidly and the open ocean starting to heat up. That means the temperature difference between the cells is, to some extent, decreasing as the arctic heats up.
There was a recent paper published by Dr. Jennifer Francis from Rutgers University arguing that as a consequence of this change, it is becoming easier to push the jet stream around. If the jet streams are more easily buckled by high pressure systems, the end result could be that extreme events like this one, caused by extreme bends in the jet stream, could become more common.
That science is still work-in-progress, but it is definitely interesting and it provides a mechanism for the increase in “extreme weather events” that has been documented in many countries over the past decade.
So that’s the U.S. right now. Extremely cold because the cold air usually trapped in the Arctic was punched to the south by a high pressure system. The world hasn't suddenly cooled down, this extremely cold air usually just sits somewhere else. And from a climate change perspective, we don’t know if events like this will become more or less common with time, but even in a climate changed world, events like this are certainly possible.
-JBB
Image credit: Greg Laden/ECMWF
Australian heat wave post:
Read more:
http://www.wunderground.com/news/polar-vortex-plunge-science-behind-arctic-cold-outbreaks-20140106