The reason this is relevant is that there is an enormous air lock down in Europe right now. The Icelandic volcano that I have posted on a number of times (here, here, and here) roared with renewed vigor yesterday, and began a new eruption phase under Eyjafjallajökull. Lava at 1100 to 1200 degrees Celsius and glaciers don't, as a rule, play nice together, and quite a bit of both components have ended up in the atmosphere.
Additionally, volcanic ash and jet turbines don't play nice together, either. The glassy ash can remelt, and foul the blades of the turbine. At best, this decreases performance of the engines; at worst, it causes complete engine failure. So when there is volcanic ash in the air, planes are advised to steer clear or stay on the ground. Often, as with earlier phases of this eruption, it's enough to simply plot a new course to avoid the area. In this phase, however...
So the above, keyed to CET, Central European Time, or GMT +2, was a bit more than 3 hours ago. The chart is part of a photogallery in today's Spiegel Online; those little gold thingies (click for full size) are flights that were in the air 2 1/2 hours earlier. According to the accompanying article,
An enormous plume of volcanic ash, invisible from the ground, has traveled from Iceland to northern Europe and grounded commercial air travel from Scandinavia and Britain to Belgium. Thousands of flights have been cancelled. Problems are expected through the weekend, and Germany hasn't been spared.(Emphasis mine) Chatting with a friend an hour or so ago, I commented that I couldn't think of a more wide-spread disruption of air travel due to volcanic ash, but apparently it's the largest disruption ever, for any cause. Is it really a greater disruption than 9/11? My suspicion is, not yet. But while the above article also has the line, "Eurocontrol estimates that air traffic will be affected for another 48 hours, " the fact is, no one knows what the volcano's plans are. It may explosively erupt sporadically for days or weeks, or it may have already gone back to sleep, as far as I know.
The Netherlands-based European Organization for the Safety of Air Navigation, or Eurocontrol, says the flight cancellations represent the most serious interruption of plane traffic in the history of air travel. Because of a massive ash plume from a volcano under the Iclandic glacier of Eyjafjallajökull, which erupted Wednesday, around one-quarter of all flights in Europe have been cancelled.
The good news is, as I said to Josh, that we know enough about volcanic eruptions to have foreseen these events as possible, and we know enough about airplanes versus volcanic ash to know to keep the former clear of the latter. We don't have to wait until aluminum tubes start falling out of the sky to avoid the problem... at least the mortally dangerous aspect of the problem. Avoiding the danger, obviously, has got to be a damned nuisance to the hundreds of thousands, perhaps even millions, of travelers whose plans have been disrupted.
As always, for the most up-to-date and trustworthy volcano news, the two blogs I recommend are Eruptions and The Volcanism Blog. These two are run by professional volcanologists, and abundant reader comments and links, combined with knowledgeable oversight, lead to timely and accurate information.
Followup, 11:12 PDT: There's another photogallery at Spiegel Online which I hadn't looked at yet. I had assumed it was the obligatory "planes on the ground, exasperated travelers, etc.," that we always see when there are travel disruptions, and which are profoundly uninformative after you've seen a few dozen of them. And there are plenty of those photos... but there are also quite a few very impressive images of the volcano and its effects as well. I had a hard time picking just one... this is number 12: Numbers 7, 10 and 13 are kind of jaw-dropping too. I'm pretty sure what we're seeing above is a jokulhaup, a sub-glacial flood burst.