Smoke and steam hangs over the volcano under the Eyjafjallajokull glacier in Iceland in this photo taken on April 14, 2010. (Jon Gustafsson/Associated Press)

Here is a by-the-numbers look at how businesses, travellers and Iceland have been affected by an ash cloud spewed by a volcano erupting beneath the Eyjafjallajokull glacier.

Grounded flights strand travellers

About 11,000 flights are expected to lift off Friday, according to Eurocontrol, the European air traffic agency. Normally there are 28,000 flights daily in European airspace.

Eurostar trains on Friday are operating at full capacity, carrying 46,000 passengers.

"There's a rush on our rental offices," said Frank Elsner, a spokesman for Germany's Sixt car rental. "We're trying to mobilize everything we can and try to offer an additional 2,000 cars across Europe in co-operation with our partners to make sure travellers can get back home on the weekend."

Shares of British Airways on Friday fell 1.1 per cent by noon while shares of Germany's Lufthansa dipped 2.1 per cent. Similarly, Air France-KLM shares dropped 1.7 per cent.

Analyst Douglas McNeill told Reuters that travel delays could cost air carriers including British Airways and Lufthansa as much as $16 million each daily.

The International Air Travel Association predicts the airlines will lose at least $200 million US per day in revenues.

About 100 aircraft have come into contact with volcanic ash from 1983 to 2000, according to the U.S. Geological Survey. Notable incidents have included the following:

• A KLM Royal Dutch Airlines Boeing 747 in 1989 lost power after passing through an ash cloud from Alaska's Redoubt volcano. The plane dropped 7,500 metres, to 3,600 metres, before the crew was able to restart its engines.
• The engine on a British Airways plane in 1982 failed after the aircraft moved through a plume of volcanic ash over Indonesia. The pilot was able to successfully restart the engines after it dropped from 11,000 metres to 3,650 metres.

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The Eyjafjallajokull glacier

The volcano beneath the Eyjafjallajokull glacier rises 1,666 metres above sea level.

The ash plume from the volcano beneath Iceland's Eyjafjallajokull glacier is seen passing over the North Atlantic on Thursday. (NASA/Associated Press)

On March 20, the volcano in the southern region of the country rumbled to life after 190 years of slumber. A fissure measuring 500 metres was observed at the top of the crater. The eruption also produced lava fountains. The same volcano on Wednesday began spewing ash skyward.

"This [volcanic ash] is like snow, it's almost like snow that covers things — grass and houses and cars about 50 kilometres east of the volcano," said Thorsteinn Jonsson, a meteorologist in Reykjavik.

About 700 people living in the countryside near the Eyjafjallajokull glacier were moved on Thursday from their homes as flash flooding washed out roads, raising safety concerns.

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Volcanic ash

Volcanic ash — composed of rock, minerals and volcanic glass — is formed during eruptions. The abrasive particles vary in size from 0.001 mm (comparable to baby powder) to two mm (coarse grit).

The cloud of ash on Friday drifted at 6,000 to 9,000 metres. The British Meteorological office also reported the cloud was expected to travel over northern France and into Russia at a speed of 40 km/h.

"Some of that ash can stay in the air and go around the globe for weeks but in concentrations sufficient to stop air traffic [it can stay up for] two or three days," said Pierre Robin, professor of geology at the University of Toronto.