The volcano in southern Iceland's Eyjafjallajokull glacier sends ash into the air just prior to sunset ON Friday, April 16, 2010. Thick drifts of volcanic ash blanketed parts of rural Iceland on Friday as a vast, invisible plume of grit drifted over Europe, emptying the skies of planes and sending hundreds of thousands in search of hotel rooms, train tickets or rental cars. (AP Photo/Brynjar Gauti) #

Long lens view of farm near the Eyjafjallajokull volcano as it continues to billow smoke and ash during an eruption late on April 17, 2010. (HALLDOR KOLBEINS/AFP/Getty Images) #

A car is seen driving near Kirkjubaejarklaustur, Iceland, through the ash from the volcano eruption under the Eyjafjallajokull glacier on Thursday April 15, 2010. (AP Photo/Omar Oskarsson) #

Chunks of ice from a glacial flood triggered by a volcanic eruption lie in front of the still-erupting volcano near Eyjafjallajokul on April 17, 2010. (REUTERS/Lucas Jackson) #

Ash covers vegetation in Eyjafjallasveit, southern Iceland April 17, 2010. (REUTERS/Ingolfur Juliusson) #

This aerial photo shows the Eyjafjallajokull volcano billowing smoke and ash on April 17, 2010. (HALLDOR KOLBEINS/AFP/Getty Images) #

A woman stands near a waterfall that has been dirtied by ash that has accumulated from the plume of an erupting volcano near Eyjafjallajokull, Iceland on April 18, 2010. (REUTERS/Lucas Jackson) #

Horses fight near the town of Sulfoss, Iceland as a volcano in Eyjafjallajokull erupts on April 17, 2010. (REUTERS/Lucas Jackson) #

Farmer Thorarinn Olafsson tries to lure his horse back to the stable as a cloud of black ash looms overhead in Drangshlid at Eyjafjoll on April 17, 2010. (REUTERS/Ingolfur Juliusson) #

A small plane (upper left) flies past smoke and ash billowing from a volcano in Eyjafjallajokul, Iceland on April 17, 2010. (REUTERS/Lucas Jackson) #

Smoke billows from a volcano in Eyjafjallajokull on April 16, 2010. (HALLDOR KOLBEINS/AFP/Getty Images) #

The sun sets in a sky dusted with ash, over Lake Geneva, as seen from the Lavaux Vineyard Terraces, a UNESCO site in Switzerland, on April 17, 2010. (FABRICE COFFRINI/AFP/Getty Images) #

The volcano in southern Iceland's Eyjafjallajokull glacier sends ash into the air Saturday, April 17, 2010. (AP Photo/Brynjar Gauti) #

Farmers team up to rescue cattle from exposure to the toxic volcanic ash at a farm in Nupur, Iceland, as the volcano in southern Iceland's Eyjafjallajokull glacier sends ash into the air Saturday, April 17, 2010. (AP Photo/Brynjar Gauti) #

A rescue team helps landowners to clear volcanic ash from a roof in Seljavellir, Iceland on April 18, 2010. (HALLDOR KOLBEINS/AFP/Getty Images) #

Sheep farmer Thorkell Eiriksson (R) and his brother-in-law Petur Runottsson work to seal a sheep barn, in case winds shift and ash from a volcano erupting across the valley lands on their farm, in Eyjafjallajokull April 17, 2010. The current season is when the spring lambs are born and such young animals are especially susceptible to volcanic ash in their lungs so they must be stored inside. (REUTERS/Lucas Jackson) #

A dark ash cloud looms over the Icelandic south coast April 17, 2010. (REUTERS/Ingolfur Juliusson) #

Lightning, smoke and lava above Iceland's Eyjafjallajokul volcano on April 17, 2010. (REUTERS/Lucas Jackson) #

View seen from a road leading to the Eyjafjallajokull volcano as it continues to billow smoke and ash during an eruption on April 17, 2010. (HALLDOR KOLBEINS/AFP/Getty Images) #

A man runs along the roadside, taking pictures of the Eyjafjallajokull volcano as it continues to billow smoke and ash during an eruption on April 17, 2010. (HALLDOR KOLBEINS/AFP/Getty Images) #

A huge ash cloud creeps over the Icelandic south coast April 16, 2010. (REUTERS/Ingolfur Juliusson) #

Wearing a mask and goggles to protect against the smoke, dairy farmer Berglind Hilmarsdottir from Nupur, Iceland, looks for cattle lost in ash clouds, Saturday, April 17, 2010. (AP Photo/Brynjar Gauti) #

A farmer checks muddy volcanic ash on his land in Iceland on April 18, 2010. (HALLDOR KOLBEINS/AFP/Getty Images) #

This aerial image shows the crater spewing ash and plumes of grit at the summit of the volcano in southern Iceland's Eyjafjallajokull glacier Saturday April 17, 2010. (AP Photo/Arnar Thorisson/Helicopter.is) #

A pilot takes pictures of the Eyjafjallajokull volcano billowing smoke and ash during an eruption on April 17, 2010. (HALLDOR KOLBEINS/AFP/Getty Images) #

Construction crews repair a road damaged by floods from glacial melting caused by a volcano in Eyjafjallajokull, Iceland April 17, 2010. (REUTERS/Lucas Jackson) #

Horses graze in a field near the Eyjafjallajokull volcano as it continues to billow dark smoke and ash during an eruption late on April 17, 2010. (HALLDOR KOLBEINS/AFP/Getty Images) #

Ingi Sveinbjoernsso leads his horses on a road covered volcanic ash back to his barn in Yzta-baeli, Iceland on April 18, 2010. They come galloping out of the volcanic storm, hooves muffled in the ash, manes flying. 24 hours earlier he had lost the shaggy Icelandic horses in an ash cloud that turned day into night, blanketing the landscape in sticky gray mud. (HALLDOR KOLBEINS/AFP/Getty Images) #

The ash plume of southwestern Iceland's Eyjafjallajokull volcano streams southwards over the Northern Atlantic Ocean in a satellite photograph made April 17, 2010. The erupting volcano in Iceland sent new tremors on April 19, but the ash plume which has caused air traffic chaos across Europe has dropped to a height of about 2 km (1.2 mi), the Meteorological Office said. (REUTERS/NERC Satellite Receiving Station, Dundee University, Scotland) #

A woman makes a phone call in the empty arrival hall of Prague's Ruzyne Airport after all flights were grounded due to volcanic ash in the skies coming from Iceland April 18, 2010. Air travel across much of Europe was paralyzed for a fourth day on Sunday by a huge cloud of volcanic ash, but Dutch and German test flights carried out without apparent damage seemed to offer hope of respite. (REUTERS/David W Cerny) #

Lava and lightning light the crater of Eyjafjallajokul volcano on April 17, 2010. (REUTERS/Lucas Jackson) #

The first of 3 photos by Olivier Vandeginste, taken 10 km east of Hvolsvollur at a distance 25 km from the Eyjafjallajokull craters on April 18th, 2010. Lightning and motion-blurred ash appear in this 15-second exposure. (© Olivier Vandeginste) #

The second of 3 photos by Olivier Vandeginste, taken 25 km from the Eyjafjallajokull craters on April 18th, 2010. The ash plume is lit from within by multiple flashes of lightning in this 168 second exposure. (© Olivier Vandeginste) #

The third of 3 photos by Olivier Vandeginste, taken 10 km east of Hvolsvollur Iceland on April 18th, 2010. Lightning flashes and glowing lava illuminate parts of Eyjafjallajokull's massive ash plume in this 30-second exposure. (© Olivier Vandeginste) #