A cloud of ash hovered over Europe on Friday, casting a pall over an interwoven world.
Made up of microscopic particles as hard as a knife's blade, the dust cloud coughed up by an Icelandic volcano crept across the industrial powerhouses of Europe, into the steppes of Russia and as far south as Hungary.
It left behind stranded travelers, grounded cargo flights, political confusion and even fears the cloud of grit settling on Earth will endanger the lungs of children, asthmatics and others with respiratory ailments.
How long it lasts and how far it spreads depends entirely on two unpredictable events: Whether the volcano beneath Iceland's Eyjafjallajokull (ay-yah-FYAH'-plah-yer-kuh-duhl) glacier keeps pumping tons of dust into the air and what wind patterns do.
The invisible cloud could split, reaching down into northern Italy, and perhaps break apart over the Alps. Scientists say the volcano could continue erupting for months, with more chaos ensuing with each big belch of basalt powder and gas.
"It's going to be a mess," said volcanologist Michael Rampino of New York University. "It's a menace to air traffic, just sitting there, waiting to go off."
Henry Margusity, senior meteorologist for AccuWeather.com, predicted the jet stream winds will continue picking up dust over Iceland and carry it to Britain and Europe "like a spray can of ash" through next Wednesday.
Is it a first? The devastating 19th-century eruption of Indonesia's Krakatau island was bigger. In ancient times, Mount Vesuvius buried an entire city and in the 17th century, a series of eruptions from Peru to the South Pacific blocked the sun's energy and sent the Earth's temperatures plunging.
But in this era of global trade crisscrossing the planet by air, the Icelandic eruption has implications that underscore the particular vulnerabilities of the modern world.
The airline industry said it was losing $200 million a day in cancellations — not counting additional costs for rerouting or taking care of grumpy passengers.
Almost two-thirds of Europe's usual 28,000 flights were grounded Friday — twice as many as a day earlier, according to the air traffic agency Eurocontrol. Air space remained closed in Britain and across large chunks of north and central Europe.
Restrictions were imposed or lifted as the cloud moved: Flights were suspended at Frankfurt airport, Europe's third-busiest, and elsewhere in Germany, while Ireland reopened airports in Dublin and Cork.
Even powerful politicians were left far from home. German Chancellor Angela Merkel, was forced to govern Europe's biggest economy from Portugal after her flight from the United States was diverted.
A new iPad helped Norway's Prime Minister Jens Stoltenberg keep in touch with his government while he was stuck in Switzerland, where he ended up after trying to fly home from the U.S.
With German air space closed, a flight carrying five German soldiers wounded in Afghanistan was diverted to Turkey; U.S. medical evacuations from Iraq and Afghanistan went directly to Washington.
Airline cancellations also brought personal anguish.
Anissa Isker arrived at Charles de Gaulle airport early Friday in hopes of taking her 8-year-old son Ryan, who has a rare genetic disease and uses a wheelchair, to Miami for treatment that could help him walk.
The hard-to-schedule treatment costs $3,000, a sum she is afraid she will lose if they can't leave this weekend.
"I think it's going to be tough, especially with my little one. When I told him we cannot leave, he got nervous," Isker told AP Television News. "Because he wants to go, he has made up his mind and he cannot understand."
Potentially lifesaving organs, too, were stuck in transit.
All organs that usually get flown out to patients were instead being distributed to those within driving distance.
"Hearts, lungs and livers, which are normally transported by air, are now delivered regionally and by ground travel," said Nadine Koerner, a spokeswoman for the German Foundation for Organ Transplant.
The World Health Organization warned the ash could cause breathing problems. Europeans, especially those with respiratory ailments or asthma, should try to stay indoors if the ash starts settling.
"We're very concerned about it," said WHO spokesman Daniel Epstein. "These particles when inhaled can reach the peripheral regions of ... the lungs and can cause problems."
Other experts, however, weren't convinced the volcanic ash would have a major health effect. Ken Donaldson, a professor of respiratory toxicology at the University of Edinburgh, said volcanic ash was much less dangerous than cigarette smoke or pollution.
With planes in Norway grounded and trains booked up, British comedian John Cleese resorted to a $5,100 (30,000 kroner) taxi ride to Brussels from Oslo, where he had taped an appearance on a Norwegian talk show Thursday night. From there, he planned to go by train to London, his publicist said.
The volcanic ash drifted at between 20,000 to 30,000 feet (6,000 to 9,000 meters), but was not a solid band of dust and particles. It was moving at around 25 miles (40 kilometers) per hour, said Harry Geurts, of the Dutch meteorological office KNMI.
Ash settled like a layer of talcum powder in parts of Iceland and lightly coated parts of Scotland, England, Norway and the Faroe Islands.
Oddly, the sun shone over much of Britain and the European low countries — more used to overcast skies than sunshine. Europe could be treated to spectacular sunsets for weeks or months to come from the lingering dust.
Rampino, the volcano expert, said the explosive power of the eruption was unusual for Iceland, where volcanic activity normally occurs as lava flows.
It may have been an interaction between the volcano's magma and the glacial ice that thrust the ash high enough to catch the winds of the jet stream sweeping toward northern Europe, he said.
"It's very difficult to predict the size, predict the behavior of a volcano," he said.
A study by Italian scientists of the dispersal of ash from the Etna eruption in 1998 highlighted the uncertainty of any predictions.
It said the trajectory of an ash cloud can change within a few hours in response to wind speeds at various heights. Particle size is also a factor: The smaller the grains of ash, the less likely they will fall to Earth.
The minuscule size of the Iceland particles makes them likely to disperse in the atmosphere unless they wash down with rain.
For now, the ash appeared unlikely to have the same cooling effect on the planet as major eruptions in history, including the 1991 eruption of Mount Pinatubo in the Philippines, which reduced temperatures and lowered sea levels for several years.
The Philippines eruption spewed up to 28 tons of sulfur dioxide into the air in two days that acted like millions of tiny mirrors reflecting sunlight back into space, said Brenda Ekwurzel, a climate scientist from the Union of Concerned Scientists in Washington.
"These are two different types of volcanos to start out with," she said. "We're still stuck with global warming."
Max reported from Amsterdam. Associated Press writers around Europe contributed to this report.
© Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.